Investigating the role of faecal calprotectin in luminal gastroenterology

Providing a sensitive, non-invasive, cheap marker of disease activity inflammatory bowel disease (IBD) comprises an area of ongoing interest and unmet clinical need. In previous years, options included only serum CRP (poorly sensitive and specific), colonoscopy (invasive, costly, perforation risk, inability to view proximal small bowel), CT (costly, ionising radiation risk) and radiolabelled white cell scanning (costly, poor sensitivity). My thesis describes a series of trials performed to establish the role of faecal calprotectin to define current disease activity in IBD patients. Prompted by studies demonstrating the potential role for a novel faecal marker of clinical utility in the context of NSAID enteropathy, we chose to investigate the role of this biomarker, faecal calprotectin (FC), in Crohn’s disease. To facilitate this I used existing cohorts and then generated new cohorts in which to address fundamental and clinically relevant questions of importance. We compared FC to radiolabelled white cell scanning in our first study which initiated and established a mutually beneficial collaboration between luminal gastroenterology and clinical biochemistry. Thereafter we recruited a rigorously phenotyped cohort of Crohn’s disease patients in remission to answer two separate research questions. First, was there a significant intra-individual variability of FC and secondly, would FC sampling in remission predict future relapse over the ensuing 12 months? Thereafter, in a new cohort, we investigated whether we were over-investigating new GP referrals to the GI clinic with only mildly elevated FC values. Finally, and most recently, we sought to investigate whether or not there was any correlation between serum calprotectin and FC in a new unselected GI cohort of patients, thereby potentially obviating the need for our patients to collect stool samples. Our data demonstrated that FC correlated well with radiolabelled white cell scanning in assessment of Crohn’s disease activity, thereby potentially avoiding this costly test as part of disease monitoring. In addition, we defined an acceptable intra-individual variability of FC in Crohn’s disease to support the clinical utility of one off testing using FC. Our prospective dataset revealed that an FC in remission can indeed stratify Crohn’s disease patients to estimate future relapse risk thereby allowing us to personalise medical therapies with more aggressive therapeutics employed in those with Crohn’s disease in remission but with residual high FC. The work we undertook in our primary care dataset revealed an extremely low yield of investigating mildly elevated FC and thus we developed a new shared protocol with our GP colleagues in which serial FC testing is recommended rather than referral to secondary care for such patients. Lastly, our most recent work demonstrated that there was no significant correlation between serum and FC in an unselected GI cohort meaning the search for a GI-specific serum biomarker of inflammation goes on – this is in accord with a variety of other chronic inflammatory diseases in which circulating biomarkers have proven challenging to find and especially to validate. This body of work has been presented nationally and internationally at meetings, and has been published in discipline relevant, peer reviewed medical journals. Moreover, it has supported the adoption of FC into everyday NHS GI practice. We were the first UK hospital to establish an NHS service for this biomarker in 2007 when we performed around 50 assays per month. Currently, the test is in widespread use and the Glasgow Royal Infirmary biochemistry lab now analyses 1400 samples per month. This has become an established non-invasive, cheap, sensitive marker of IBD activity in clinical practice, often avoiding the need for colonoscopy for the purposes of disease activity monitoring. This biomarker is also being used to gauge the success or failure of medical therapies in IBD and is a useful tool to differentiate irritable bowel syndrome from IBD. The clinical utility of the test has allowed GPs to triage referrals and often avoid referrals completely and has engaged patients in the self-monitoring of their IBD

Dietary treatment of Crohn’s disease: perceptions of families with children treated by exclusive enteral nutrition, a questionnaire survey

Background: Diet is strongly associated with the aetiology of Crohn’s Disease (CD) and exclusive enteral nutrition (EEN) is the primary induction treatment in paediatric CD. This study explored opinions around the use of EEN and alternative novel, solid food-based diets (SFDs) expressed by paediatric patients with CD, previously treated with EEN and their parents. Methods: This anonymous questionnaire surveyed families of CD patients treated with EEN over 1 year. Two questionnaire forms were completed; one asking the patients’ opinions and another referring to their main carer. This questionnaire explored participants’ demographic characteristics; acceptability of a repeat EEN course to treat a future flare (EEN repeat); their opinion on how difficult EEN would be compared to an example SFD; and their intention to participate in a future clinical trial assessing the therapeutic efficacy of an SFD in CD. Results: Forty-one families of CD patients were approached with 29 sending replies (71%). Most of our participants were positive on completing another EEN course, however the majority would choose an SFD alternative (Patients: 66, Parents:72%). Both patients and their parents rated EEN to be more difficult to adhere to compared to an example SFD (p < 0.05), and their ratings were strongly correlated (EEN:r = 0.83, SFD:r = 0.75, p < 0.001). The majority of our respondents would agree to participate in a clinical trial assessing an SFD’s effectiveness (Patients:79, Parents:72%) for the management of active CD. Conclusions: While patients with CD and their families would accept an EEN repeat, the majority would prefer an SFD alternative. CD families surveyed are supportive of the development of solid food-based dietary treatments

The distinct features of microbial 'dysbiosis' of Crohn's disease do not occur to the same extent in their unaffected, genetically linked kindred

Background/Aims: Studying the gut microbiota in unaffected relatives of people with Crohn’s disease (CD) may advance our understanding of the role of bacteria in disease aetiology. Methods: Faecal microbiota composition (16S rRNA gene sequencing), genetic functional capacity (shotgun metagenomics) and faecal short chain fatty acids (SCFA) were compared in unaffected adult relatives of CD children (CDR, n = 17) and adult healthy controls, unrelated to CD patients (HUC, n = 14). The microbiota characteristics of 19 CD children were used as a benchmark of CD ‘dysbiosis’. Results: The CDR microbiota was less diverse (p = 0.044) than that of the HUC group. Local contribution of β-diversity analysis showed no difference in community structure between the CDR and HUC groups. Twenty one of 1,243 (1.8%) operational taxonomic units discriminated CDR from HUC. The metagenomic functional capacity (p = 0.207) and SCFA concentration or pattern were similar between CDR and HUC (p>0.05 for all SCFA). None of the KEGG metabolic pathways were different between these two groups. Both of these groups (HUC and CDR) had a higher microbiota α-diversity (CDR, p = 0.026 and HUC, p<0.001) with a community structure (β-diversity) distinct from that of children with CD. Conclusions: While some alterations were observed, a distinct microbial ‘dysbiosis’, characteristic of CD patients, was not observed in their unaffected, genetically linked kindred

Structural and Energetic Mechanisms of Cooperative Autoinhibition and Activation of Vav1

SummaryVav proteins are guanine nucleotide exchange factors (GEFs) for Rho family GTPases. They control processes including T cell activation, phagocytosis, and migration of normal and transformed cells. We report the structure and biophysical and cellular analyses of the five-domain autoinhibitory element of Vav1. The catalytic Dbl homology (DH) domain of Vav1 is controlled by two energetically coupled processes. The DH active site is directly, but weakly, inhibited by a helix from the adjacent Acidic domain. This core interaction is strengthened 10-fold by contacts of the calponin homology (CH) domain with the Acidic, pleckstrin homology, and DH domains. This construction enables efficient, stepwise relief of autoinhibition: initial phosphorylation events disrupt the modulatory CH contacts, facilitating phosphorylation of the inhibitory helix and consequent GEF activation. Our findings illustrate how the opposing requirements of strong suppression of activity and rapid kinetics of activation can be achieved in multidomain systems

Patients with inflammatory bowel disease have higher abdominal adiposity and less skeletal mass than healthy controls

Background Abdominal fat type and distribution have been associated with complicated Crohn’s disease and adverse postoperative outcomes. Few studies have assessed the abdominal distribution of fat and lean stores in patients with inflammatory bowel disease (IBD) and compared this with healthy controls. This retrospective study aimed to compare the abdominal body composition in IBD patients who failed medical treatment and who underwent computed tomography (CT) imaging prior to gastrointestinal surgery with healthy controls. Associations between preoperative abdominal body composition and postoperative outcomes within a year of surgery were explored. Methods Abdominal body composition was evaluated in 22 presurgical patients with medically refractory IBD (18 with Crohn’s disease) and 22 healthy controls, using routinely acquired CT. Total fat, subcutaneous fat, visceral fat, and skeletal muscle cross-sectional area were measured. Results An independent disease effect was observed, explaining a fat deposition excess of 38 cm2 and a skeletal muscle deficit of 15 cm2 in IBD. Abdominal skeletal muscle correlated with visceral fat for the control (rho=0.51, P=0.015), but not for the IBD group (rho=-0.13, P=0.553). A positive correlation observed between subcutaneous fat with skeletal muscle in the controls (rho=0.47, P=0.026) was inverted in the IBD group (rho=-0.43, P=0.045). Preoperative abdominal body composition was not predictive of postoperative outcomes. Conclusions A higher degree of abdominal adiposity, a lower skeletal mass and a larger body size for the same anthropometry can be expected in IBD patients. Preoperative abdominal body composition is not associated with surgical outcomes. Keywords Inflammatory bowel disease, computed tomography, body compositio

A prospective analysis of micronutrient status in quiescent inflammatory bowel disease

Background and aims: ESPEN guidelines advocate patients with inflammatory bowel disease (IBD) have their micronutrient levels checked regularly. This study described the micronutrient status of patients with quiescent IBD and explore whether biochemical micronutrient deficiencies related to time to subsequent disease relapse. Methods: Sixteen micronutrients were measured prospectively in blood of patients with IBD in clinical remission [Harvey Bradshaw Index (HBI) ≤4 in Crohn's disease (CD) and a partial Mayo score <2 in ulcerative colitis (UC)]. Patients were followed prospectively using the electronic patient records. The ability of micronutrient status to predict time to relapse was tested with survival analysis and Cox regression. Results: Ninety-three patients were enrolled; Fifty (54%) were also in biochemical remission defined as a normal faecal calprotectin (<250 μg/g), C-reactive protein (<10 mg/L) and serum albumin (>35 g/L). Deficiencies in vitamin D were identified in 27 (29%), zinc in 15 (16%), vitamin B6 in 13 (14%), vitamin C in 12 (13%) and vitamin B12 in 10 (11%). Fewer participants had low serum folate 7 (8%), ferritin 8 (9%), copper 4 (4%), magnesium 4 (4%) and plasma selenium 3 (3%). Zinc deficiency was predictive of a shorter time to subsequent relapse (HR: 6.9; 95%CI [1.9 to 26], p = 0.008); in sub analysis of those with CD this effect was even more profound (p = 0.001). Conclusion: We identified biochemical deficiencies for several micronutrients among adults with IBD clinically in remission. We have also highlighted a significant association between zinc deficiency and time to subsequent disease relapse in patients with CD which needs further investigation

A prospective evaluation of the predictive value of faecal calprotectin in quiescent Crohn’s disease

Background: The faecal calprotectin (FC) test is a non-invasive marker for gastrointestinal inflammation. Aim: To determine whether higher FC levels in individuals with quiescent Crohn’s disease are associated with clinical relapse over the ensuing 12 months.<p></p> Methods: A single centre prospective study was undertaken in Crohn's disease patients in clinical remission attending for routine review. The receiver operating characteristic (ROC) curve for the primary endpoint of clinical relapse by 12 months, based on FC at baseline, was calculated. Kaplan-Meier curves of time to relapse were based on the resulting optimal FC cutoff for predicting relapse.<p></p> Results: Of 97 patients recruited, 92 were either followed up for 12 months without relapsing, or reached the primary endpoint within that period. Of these, 10 (11%) had relapsed by 12 months. The median FC was lower for non-relapsers, 96µg/g (IQR 39-237), than for relapsers, 414µg/g (IQR 259-590), (p=0.005). The area under the ROC curve to predict relapse using FC was 77.4%. An optimal cutoff FC value of 240µg/g to predict relapse of quiescent Crohn’s had sensitivity of 80.0% and specificity of 74.4%. Negative predictive value was 96.8% and positive predictive value was 27.6%. FC≥240μg/g was associated with likelihood of relapse 5.7 (95% CI 1.9-17.3) times higher within 2.3 years than lower values (p=0.002).<p></p> Conclusions: In this prospective dataset, FC appears to be a useful, non-invasive tool to help identify quiescent Crohn’s disease patients at a low risk of relapse over the ensuing 12 months. FC of 240µg/g was the optimal cutoff in this cohort.<p></p&gt

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Durvalumab (MEDI 4736) in combination with extended neoadjuvant regimens in rectal cancer : a study protocol of a randomised phase II trial (PRIME-RT)

Acknowledgements We are grateful to Mr George Davidson and Ms Monica Jeffers for their input with writing the PRIME-RT protocol and patient information sheet. This study is co-sponsored by the University of Glasgow and NHS Greater Glasgow and Clyde. Funding PRIME-RT is funded by Astrazeneca and receives core funding from CRUK Clinical Trials Unit Glasgow for the purposes of trial set-up and data collection. The trial is co-sponsored by the University Of Glasgow and NHS Greater Glasgow and Clyde.Peer reviewedPublisher PD