Clinical Utility of Biomarkers in IBD

Diagnosis and Differentiation of Inflammatory Bowel Disease

Differentiating Crohn's disease from ulcerative colitis may be a diagnostic challenge for clinicians due to overlapping features. However, the correct diagnosis may guide treatment options and considerations regarding surgery. This study reviews the common components of diagnostic evaluation of inflammatory bowel disease. Additionally, this article provides a basis of understanding for the more complex aspects of the disease to be discussed in subsequent studies.

The role of new inflammatory indices in the prediction of endoscopic and histological activity in inflammatory bowel disease patients

BACKGROUND AND AIM

Inflammatory indices are promising indicators that can be used to evaluate inflammation in inflammatory bowel diseases (IBDs). The present study aimed to investigate the test accuracy of several inflammatory indices to identify endoscopic, and histological activity in a cohort of IBD patients.

STUDY

All IBD patients who underwent colonoscopy and blood examination (within 4 weeks and without therapeutic change) were included. For these patients, 10 different inflammatory biomarkers were collected. Our primary outcome was the assessment of accuracy [evaluated with a receiver operating characteristics (ROC) analysis] of each inflammatory biomarker and indices. Furthermore, we tried to establish the optimal cutoff to identify patients with endoscopic and histologic activity among the inflammatory biomarkers and indices with higher performance.

RESULTS

Regarding endoscopic activity, at the ROC analysis, the systemic inflammation response index (SIRI) showed the best accuracy [area under the curve (AUC), 0.627; confidence interval (CI), 0.552-0.698]. Whereas the ROC analysis showed a suboptimal AUC for the neutrophil-to-lymphocytes ratio (NLR) and platelets-to-lymphocytes ratio; (AUC, 0.620; CI, 0.545-0.691 and AUC, 0.607; CI, 0.532-0.679, respectively). Concerning histological activity, the C-reactive protein albumin ratio (CAR) presented a higher accuracy among the calculated inflammatory biomarkers (AUC, 0.682; CI, 0.569-0.781) while SIRI and NLR presented a subdued diagnostic performance.

CONCLUSION

SIRI and CAR presented the best test accuracy in an IBD outpatient setting to identify endoscopic and histological activity. However, the test accuracy of all the evaluated Inflammatory indices appeared suboptimal. Fecal calprotectin has still the highest accuracy in predicting endoscopic and histological activity in patients with IBD.

miRNAs Can Affect Intestinal Epithelial Barrier in Inflammatory Bowel Disease

The most obvious pathological characterization of inflammatory bowel disease (IBD) is intestinal epithelium erosion and severe inflammation invasion. Micro-ribonucleic acids (miRNA or microRNA), single-stranded noncoding RNAs of ~22 nucleotides, have been considered as the potential therapeutic targets in the pathogenesis of IBD. Many previous studies have focused on the mechanisms that miRNAs use to regulate inflammation, immunity, and microorganisms in IBD. The review highlights in detail the findings of miRNAs in the intestinal epithelial barrier of IBD, and focuses on their gene targets, signaling pathways associated with IBD, and some potential therapies. It will be beneficial for the elucidation of the interaction between miRNAs and the intestinal epithelial barrier in IBD and provide a theoretical reference for preventing and treating IBD in the future.

The exercise-induced inflammatory response in inflammatory bowel disease: A systematic review and meta-analysis

BACKGROUND

This study investigated selected inflammatory responses to acute and chronic exercise in individuals with inflammatory bowel disease (IBD).

METHODS

A systematic review and meta-analysis was conducted on all relevant exercise-based intervention publications with IBD participants. The study included articles that utilised a broad range of acute and chronic exercise interventions, with inflammatory biomarkers measured and symptoms documented, both pre- and post-exercise for those with IBD. The search was limited to studies published in English, the use of human participants, and primary studies, with no restrictions on date of publication or participant's age. Articles were retrieved through the electronic databases: PubMed, SPORTDiscus, and Scopus. This study adhered to Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines.

RESULTS

Six inflammatory markers were included in the meta-analysis which consisted of five studies. Exercise interventions resulted in no significant difference in IL-6 (SMD = -0.09; 95% CI = -0.49, 0.30; P = 0.64), TNF-α (SMD = 0.08; 95% CI = -0.31, 0.48; P = 0.68), CRP (SMD = -0.04; 95% CI = -0.58, 0.50; P = 0.89), IL-17 (SMD = 0.15; 95% CI = -0.45, 0.76; P = 0.62), leukocytes (SMD = 0.40; 95% CI = -0.53, 1.33; P = 0.40) or lymphocytes (SMD = 0.32; 95% CI = -0.33, 0.97; P = 0.33), thus, indicating exercise may have no effect on inflammatory markers in IBD. Bowel symptoms improved following regular moderate exercise that incorporated stress management.

CONCLUSION

Heterogeneity among the identified literature may have led to exercise interventions being ineffective in reducing inflammation. Although the limited number of eligible studies may reduce the reliability of results, it emphasises the need for additional research in this domain. Importantly, no adverse symptomatic responses to exercise indicate that exercise is safe for IBD patients.

Use of helminth therapy for management of ulcerative colitis and Crohn's disease: a systematic review

The incidence rate of inflammatory bowel diseases is increasing in developed countries. As such there is an increasing demand for new therapies. The aim of this systematic review was to investigate whether there is evidence to support the use of helminth therapy for the management of Crohn's disease and ulcerative colitis. Four databases (PubMed, Embase, Medline and the Cochrane Central Register of Control Trials) were searched for primary evidence in the form of clinical studies. Nine studies were suitable for inclusion: five double-blind randomized control trials and four open-label studies. This review divided the results of the studies into two categories: (a) the efficacy of helminth therapy and (b) the safety of helminth therapy. Results regarding the efficacy were mixed and a conclusive answer could not be reached, as there was not enough evidence to rule out a placebo effect. More research is needed, particularly studies with control groups to address the possibility of a placebo effect. Despite this, all nine studies concluded helminth therapy was safe and tolerable, and therefore there is currently no evidence against further exploration of this treatment option.

Serum Interleukin (IL)-23 and IL-17 Profile in Inflammatory Bowel Disease (IBD) Patients Could Differentiate between Severe and Non-Severe Disease

Interleukin (IL)-17 and IL-23 are crucial for mediating gut mucosal inflammation in inflammatory bowel disease (IBD), which has led to new therapeutic strategies. We assessed the relevancy of IL-17 and IL-23 serum levels as potential biomarkers towards severe IBD discrimination and disease-related complications. Sixty-two patients diagnosed with Crohn's disease (CD) and ulcerative colitis (UC) were included. Serum IL-17 and IL-23 were measured by sandwich enzyme-linked immunosorbent assays (ELISA). IL-23 and fecal calprotectin (FCal) were significantly higher in severe CD (p < 0.001) and UC (p < 0.001 and p = 0.001, respectively), compared to mild or moderate. Elevated C-reactive protein (CRP) was correlated with severe disease only in CD (p = 0.008), whereas for UC, disease severity was associated with increased IL-17 values (p < 0.001). Diagnostic role of IL-23 was superior to FCal in discriminating between severe and mild to moderate CD (p < 0.001). IL-23 levels were also significantly higher in CD patients with intestinal complications (p = 0.04). Both IL-17 and IL-23 correlate with IBD severity, and IL-23 might be a promising novel biomarker for severe CD. Identifying the dominant IL pathway involved in IBD severity could serve as guidance for clinical decision-making on biologic therapy.

Peptidomic and proteomic analysis of stool for diagnosing IBD and deciphering disease pathogenesis

Background The sensitivities and specificities of C-reactive protein (CRP) and faecal calprotectin (fCal), as recommended for inflammatory bowel diseases (IBD) diagnosis and monitoring, are low. Our aim was to discover new stool protein/peptide biomarkers for diagnosing IBD. Methods For peptides, MALDI-TOF/MS (m/z 1000-4000) was performed using stools from an exploratory (34 controls; 72 Crohn's disease [CD], 56 ulcerative colitis [UC]) and a validation (28 controls, 27 CD, 15 UC) cohort. For proteins, LTQ-Orbitrap XL MS analysis (6 controls, 5 CD, 5 UC) was performed. Results MALDI-TOF/MS spectra of IBD patients had numerous features, unlike controls. Overall, 426 features (67 control-associated, 359 IBD-associated) were identified. Spectra were classified as control or IBD (absence or presence of IBD-associated features). In the exploratory cohort, the sensitivity and specificity of this classification algorithm were 81% and 97%, respectively. Blind analysis of the validation cohort confirmed 97% specificity, with a lower sensitivity (55%) paralleling active disease frequency. Following binary logistic regression analysis, IBD was independently correlated with MALDI-TOF/MS spectra (p < 0.0001), outperforming fCal measurements (p = 0.029). The IBD-correlated m/z 1810.8 feature was a fragment of APC2, homologous with APC, over-expressed by infiltrating cells lining the surface in UC or the muscularis-mucosae in CD (assessed by immunohistochemistry). IBD-associated over-expressed proteins included immunoglobulins and neutrophil proteins, while those under-expressed comprised proteins of the nucleic acid assembly or those (OLFM4, ENPP7) related to cancer risk. Conclusions Our study provides evidence for the clinical utility of a novel proteomic method for diagnosing IBD and insight on the pathogenic role of APC. Moreover, the newly described IBD-associated proteins might become tools for cancer risk assessment in IBD patients.

MicroRNA-320a Monitors Intestinal Disease Activity in Patients With Inflammatory Bowel Disease

In patients with inflammatory bowel disease (IBD), a treat-to-target treatment strategy requires tight monitoring of disease activity. Noninvasive biomarkers may help to monitor the intestinal disease activity. We demonstrated recently that peripheral microRNA (miR)-320a expression in mice follows the course of experimental colitis. The aim of this study was to evaluate the potential of miR-320a to monitor the disease activity in patients with IBD, to predict the course of disease, and to distinguish IBD from infectious colitis.

Global Studies of Using Fecal Biomarkers in Predicting Relapse in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract mainly comprising two forms including Crohn's disease (CD) and ulcerative colitis (UC). IBD is a lifelong relapsing remitting disease and relapses occur at random patterns which are unpredictable. Fecal biomarkers have been increasingly used to assess disease activity in IBD due to their positive correlations with intestinal inflammation. Recent studies have also assessed the use of fecal biomarkers in predicting relapse and post-operative recurrence. This review provides information from global studies of using fecal calprotectin, lactoferrin and S100A12 to predict relapse in IBD. Strategies for further studies and the use of these fecal biomarkers for personalized management in IBD are also discussed.

Assessment of disease activity in inflammatory bowel diseases: Non-invasive biomarkers and endoscopic scores

Inflammatory bowel diseases (IBD) comprise two major forms: Crohn's disease and ulcerative colitis. The diagnosis of IBD is based on clinical symptoms combined with results found in endoscopic and radiological examinations. In addition, the discovery of biomarkers has significantly improved the diagnosis and management of IBD. Several potential genetic, serological, fecal, microbial, histological and immunological biomarkers have been proposed for IBD, and they have been evaluated for clinical routine and clinical trials. Ileocolonoscopy, especially with biopsy collection, has been considered the standard method to diagnose IBD and to assess clinical activity of the disease, but it is limited to the colon and terminal ileum and is considered invasive. For this reason, non-invasive biomarkers are necessary for this type of chronic inflammatory disease, which affects mostly young individuals, as they are expected to have a long follow-up.

Role of regenerating islet-derived proteins in inflammatory bowel disease

Inflammatory bowel disease (IBD) is an inflammatory disorder of the gastrointestinal tract that affects millions of patients worldwide. It has a complex and multifactorial etiology leading to excessive exposure of intestinal epithelium to microbial antigens, inappropriate activation of the immune system and ultimately to the damage of intestinal tissues. Although numerous efforts have been made to improve the disease management, IBD remains persistently recurring and beyond cure. This is due largely to the gaps in our understanding of the pathogenesis of IBD that hamper the development of timely diagnoses and effective treatment. However, some recent discoveries, including the beneficial effects of interleukin-22 (IL-22) on the inflamed intestine, have shed light on a self-protective mechanism in IBD. Regenerating islet-derived (REG/Reg) proteins are small secretory proteins which function as IL-22's downstream effectors. Mounting studies have demonstrated that IBD patients have significantly increased REG expressions in the injured intestine, but with undefined mechanisms and roles. The reported functions of REG/Reg proteins in intestinal homeostasis, such as those of antibacterial, anti-inflammatory and tissue repair, lead us to discuss their potential mechanisms and clinical relevance in IBD in order to advance IBD research and management.

Non-SMC condensin I complex subunit D2 and non-SMC condensin II complex subunit D3 induces inflammation via the IKK/NF-κB pathway in ulcerative colitis

BACKGROUND

Ulcerative colitis (UC) is a chronic, nonspecific intestinal inflammatory disease with undefined pathogenesis. Non-SMC condensin I complex subunit D2 (NCAPD2) and non-SMC condensin II complex subunit D3 (NCAPD3) play pivotal roles in chromosome assembly and segregation during both mitosis and meiosis. To date, there has been no relevant report about the functional role of NCAPD2 and NCAPD3 in UC.

AIM

To determine the level of NCAPD2/3 in intestinal mucosa and explore the mechanisms of NCAPD2/3 in UC.

METHODS

Levels of NCAPD2/3 in intestinal tissue were detected in 30 UC patients and 30 healthy individuals with in situ hybridization (ISH). In vitro, NCM60 cells were divided into the NC group, model group, si-NCAPD2 group, si-NCAPD3 group and si-NCAPD2+si-NCAPD3 group. Inflammatory cytokines were measured by ELISA, IKK and NF-κB were evaluated by western blot, and IKK nucleation and NF-κB volume were analyzed by immunofluorescence assay.

RESULTS

Compared with expression in healthy individuals, NCAPD2 and NCAPD3 expression in intestinal tissue was significantly upregulated (P < 0.001) in UC patients. Compared with levels in the model group, IL-1β, IL-6 and TNF-α in the si-NCAPD2, si-NCAPD3 and si-NCAPD2+si-NCAPD3 groups were significantly downregulated (P < 0.01). IKK and NF-κB protein expression in the si-NCAPD2, si-NCAPD3 and si-NCAPD2+si-NCAPD3 groups was significantly decreased (P < 0.01). Moreover, IKK nucleation and NF-κB volume were suppressed upon si-NCAPD2, si-NCAPD3 and si-NCAPD2+ si-NCAPD3 transfection.

CONCLUSION

NCAPD2/3 is highly expressed in the intestinal mucosa of patients with active UC. Overexpression of NCAPD2/3 promotes the release of pro-inflammatory cytokines by modulating the IKK/NF-κB signaling pathway.

Oversecretion and Overexpression of Nicotinamide Phosphoribosyltransferase/Pre-B Colony-Enhancing Factor/Visfatin in Inflammatory Bowel Disease Reflects the Disease Activity, Severity of Inflammatory Response and Hypoxia

Nicotinamide phosphoribosyltransferase's (Nampt) association with inflammatory bowel disease (IBD) is unclear. The study was aimed at unraveling Nampt's clinical and diagnostic relevance. The serum concentration (Luminex-xMAP® technology) was measured in 113 patients with Crohn's disease (CD), 127 with ulcerative colitis (UC) and 60 non-IBD controls: 40 healthy individuals and 20 with irritable bowel syndrome (IBS). The leukocyte (44 CD/37 UC/19 IBS) and bowel expression (186 samples) was also evaluated (RT-qPCR). All were referred to IBD phenotype, activity, treatment, and inflammatory/nutritional/angiogenic/hypoxia indices. Serum-Nampt and leukocyte-Nampt were positively correlated and were more elevated in active-IBD than in IBS, with leukocyte-Nampt being a fair differential marker. Serum-Nampt in UC positively correlated with its clinical and endoscopic activity as well as with pro-inflammatory cytokines. Serum-Nampt ≤1.54 ng/mL was a good indicator of mucosal healing. The expression of Nampt was up-regulated both in inflamed and quiescent colon and reflected, similarly to leukocyte-Nampt, the clinical activity of IBD. Bowel-Nampt was independently associated with IL1B and hypoxia-inducible factor 1α (HIF1A) expression in inflamed bowel but with FGF2 expression in quiescent bowel. In summary, Nampt's elevation in IBD at local and systemic levels, and protein and mRNA levels, reflects IBD activity and is associated with inflammation, hypoxia (active) and tissue repair (inactive disease).

Peripheral Lymphocytes of Patients with Inflammatory Bowel Disease Have Altered Concentrations of Key Apoptosis Players: Preliminary Results

Notwithstanding uncertain pathogenesis of inflammatory bowel disease (IBD), deregulation of adaptive immunity is paramount for the development of inflammation. Essential role in the resolution of inflammation is played by apoptosis, deregulated in lymphocytes isolated from inflamed intestine. Despite IBD being a systemic disease, little is known about apoptosis of peripheral lymphocytes. The concentrations of Bcl-2, cytochrome c, p53, and caspase-9 were determined (ELISA) in lymphocyte-enriched fractions of peripheral blood mononuclear cells (LE-PBMCs) from 64 individuals (42 with IBD) and related to IBD phenotype and activity, treatment, and inflammatory and hematological indices. The diagnostic potential of evaluated markers was determined as well. All evaluated molecules were significantly lower in IBD patients, of which cytochrome c and p53 were significantly lower exclusively in patients with Crohn's disease (CD) and cytochrome c differed significantly between CD and ulcerative colitis (UC). Caspase 9 was significantly lower in active IBD and Bcl-2 in active UC whereas cytochrome c was higher in active CD. Treatment with corticosteroids affected the concentrations of cytochrome c and p53. Both positively correlated with hsCRP and the concentrations of all markers were interrelated. As IBD markers, Bcl-2 and caspase-9 displayed good accuracy and, as a panel of markers with cytochrome c, their accuracy was excellent (92%). As CD markers Bcl-2, cytochrome c, and p53 displayed fair accuracy but combined determination of Bcl-2 and cytochrome c improved the accuracy to 85%. Taken together, our results imply diminished intrinsic apoptotic capacity of LE-PBMCs in IBD but an upregulation of proapoptotic features parallel to increasing severity of inflammation. Observed abnormalities in intrinsic pathway of apoptosis are more pronounced in CD. Upon positive validation on a larger set of patients, combined quantification of Bcl-2 and cytochrome c might be considered as an adjunct in differential diagnosis of UC and CD of colon and rectum.

Expression of CCR6 and CXCR6 by Gut-Derived CD4+/CD8α+ T-Regulatory Cells, Which Are Decreased in Blood Samples From Patients With Inflammatory Bowel Diseases

BACKGROUND & AIMS

Faecalibacterium prausnitzii, a member of the Clostridium IV group of the Firmicutes phylum that is abundant in the intestinal microbiota, has anti-inflammatory effects. The relative level of F prausnitzii is decreased in fecal samples from patients with inflammatory bowel diseases (IBDs) compared with healthy individuals. Reduced F prausnitzii was correlated with relapse of Crohn's disease after surgery. We identified, in human colonic mucosa and blood, a population of T regulatory type 1-like T regulatory (T_REG) cells that express CD4 and CD8α (DP8α T cells) and are specific for F prausnitzii. We aimed to determine whether they are altered in patients with IBD.

METHODS

We isolated DP8α T cells from human colon lamina propria and blood samples and used flow cytometry to detect markers of cells that are of colon origin. We quantified DP8α cells that express colon-specific markers in blood samples from 106 patients with IBD, 12 patients with infectious colitis, and 35 healthy donors (controls). We identified cells that respond to F prausnitzii. Cells were stimulated with anti-CD3, and their production of interleukin 10 was measured by enzyme-linked immunosorbent assay. We compared the frequency and reactivity of cells from patients vs controls using the 2-sided Student t test or 1-way analysis of variance.

RESULTS

Circulating DP8α T cells that proliferate in response to F prausnitzii express the C-C motif chemokine receptor 6 (CCR6) and C-X-C motif chemokine receptor 6 (CXCR6). These cells also have features of T_REG cells, including production of IL-10 and inhibition of T-cell proliferation via CD39 activity. The proportion of circulating CCR6⁺/CXCR6⁺ DP8α T cells was significantly reduced (P < .0001) within the total population of CD3⁺ T cells from patients with IBD compared with patients with infectious colitis or controls. A threshold of <7.875 CCR6⁺/CXCR6⁺ DP8α T cells/10,000 CD3⁺ cells discriminated patients with IBD from those with infectious colitis with 100% specificity and 72.2% sensitivity.

CONCLUSIONS

We identified a population of gut-derived T_REG cells that are reduced in blood samples from patients with IBD compared with patients with infectious colitis or controls. These cells should be studied further to determine the mechanisms of this reduction and how it might contribute to the pathogenesis of IBD and their prognostic or diagnostic value.

Proteomics and Lipidomics in Inflammatory Bowel Disease Research: From Mechanistic Insights to Biomarker Identification

Inflammatory bowel disease (IBD) represents a group of progressive disorders characterized by recurrent chronic inflammation of the gut. Ulcerative colitis and Crohn's disease are the major manifestations of IBD. While our understanding of IBD has progressed in recent years, its etiology is far from being fully understood, resulting in suboptimal treatment options. Complementing other biological endpoints, bioanalytical "omics" methods that quantify many biomolecules simultaneously have great potential in the dissection of the complex pathogenesis of IBD. In this review, we focus on the rapidly evolving proteomics and lipidomics technologies and their broad applicability to IBD studies; these range from investigations of immune-regulatory mechanisms and biomarker discovery to studies dissecting host⁻microbiome interactions and the role of intestinal epithelial cells. Future studies can leverage recent advances, including improved analytical methodologies, additional relevant sample types, and integrative multi-omics analyses. Proteomics and lipidomics could effectively accelerate the development of novel targeted treatments and the discovery of complementary biomarkers, enabling continuous monitoring of the treatment response of individual patients; this may allow further refinement of treatment and, ultimately, facilitate a personalized medicine approach to IBD.

Epithelial Barrier Function in Gut-Bone Signaling

The intestinal epithelial barrier plays an essential role in maintaining host homeostasis. The barrier regulates nutrient absorption as well as prevents the invasion of pathogenic bacteria in the host. It is composed of epithelial cells, tight junctions, and a mucus layer. Several factors, such as cytokines, diet, and diseases, can affect this barrier. These factors have been shown to increase intestinal permeability, inflammation, and translocation of pathogenic bacteria. In addition, dysregulation of the epithelial barrier can result in inflammatory diseases such as inflammatory bowel disease. Our lab and others have also shown that barrier disruption can have systemic effects including bone loss. In this chapter, we will discuss the current literature to understand the link between intestinal barrier and bone. We will discuss how inflammation, aging, dysbiosis, and metabolic diseases can affect intestinal barrier-bone link. In addition, we will highlight the current suggested mechanism between intestinal barrier and bone.

Circulating cathelicidin levels correlate with mucosal disease activity in ulcerative colitis, risk of intestinal stricture in Crohn's disease, and clinical prognosis in inflammatory bowel disease

Background

Cathelicidin (LL-37) is an antimicrobial peptide known to be associated with various autoimmune diseases. We attempt to determine if cathelicidin can accurately reflect IBD disease activity. We hypothesize that serum cathelicidin correlates with mucosal disease activity, stricture, and clinical prognosis of IBD patients.

Methods

Serum samples were collected from two separate cohorts of patients at the University of California, Los Angeles. Cohort 1 consisted of 50 control, 23 UC, and 28 CD patients. Cohort 2 consisted of 20 control, 57 UC, and 67 CD patients. LL-37 levels were determined by ELISA. Data from both cohorts were combined for calculation of accuracies in indicating mucosal disease activity, relative risks of stricture, and odds ratios of predicting disease development.

Results

Serum cathelicidin levels were inversely correlated with Partial Mayo Scores of UC patients and Harvey-Bradshaw Indices of CD patients. Among IBD patients with moderate or severe initial disease activity, the patients with high initial LL-37 levels had significantly better recovery than the patients with low initial LL-37 levels after 6–18 months, suggesting that high LL-37 levels correlate with good prognosis. Co-evaluation of LL-37 and CRP levels was more accurate than CRP alone or LL-37 alone in the correlation with Mayo Endoscopic Score of UC patients. Low LL-37 levels indicated a significantly elevated risk of intestinal stricture in CD patients.

Conclusion

Co-evaluation of LL-37 and CRP can indicate mucosal disease activity in UC patients. LL-37 can predict future clinical activity in IBD patients and indicate risk of intestinal stricture in CD patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12876-017-0619-4) contains supplementary material, which is available to authorized users.

Urinary metabolites as noninvasive biomarkers of gastrointestinal diseases: A clinical review

The diagnosis of gastrointestinal (GI) disorders is usually based on invasive techniques such as endoscopy. A key important factor in GI cancer is early diagnosis which warrants development of non- or less-invasive diagnostic techniques. In addition, monitoring and surveillance are other important parts in the management of GI diseases. Metabolomics studies with nuclear magnetic resonance and mass spectrometry can measure the concentration of more than 3000 chemical compounds in the urine providing possible chemical signature in different diseases and during health. In this review, we discuss the urinary metabolomics signature of different GI diseases including GI cancer and elaborate on how these biomarkers could be used for the classification, early diagnosis and the monitoring of the patients. Moreover, we discuss future directions of this still evolving field of research.

Relationship of clinical symptoms with biomarkers of inflammation in pediatric inflammatory bowel disease

In adult inflammatory bowel disease (IBD) patients, there is a strong discrepancy between symptoms and biomarkers of inflammation. Data on pediatric IBD patients are conflicting. Therefore, we aimed to investigate the relationship between clinical symptoms and biomarkers of inflammation in pediatric IBD. Patients aged <18 years with previously diagnosed Crohn's disease (CD) or ulcerative colitis (UC) were included. Clinical disease activity was determined using the abbreviated Pediatric CD Activity Index (aPCDAI) or Pediatric UC Activity Index (PUCAI). Biochemical disease activity was assessed using fecal calprotectin (FC) and C-reactive protein (CRP). In total, 127 patients (62 male; median age 14.9 years) were included (82 CD, 45 UC). FC correlated weakly with total aPCDAI score (r s = 0.32; 95 % CI 0.12-0.51; p = 0.003) and total PUCAI score (r s = 0.36; 95 % CI 0.07-0.62; p = 0.015). Only aPCDAI components abdominal examination and perirectal disease and PUCAI component activity level had a significant correlation with levels of FC. CRP correlated weakly with total aPCDAI score (r s = 0.28; 95 % CI 0.05-0.46; p = 0.012) and aPCDAI components abdominal examination and activity level. No significant correlation was observed between CRP and total PUCAI score (r s = 0.01; 95 % CI -0.34-0.29; p = 0.961) or individual PUCAI components.

CONCLUSION

There is a strong discrepancy between clinical symptoms and biomarkers of inflammation in children with IBD.

WHAT IS KNOWN

• A substantial proportion of asymptomatic pediatric inflammatory bowel disease (IBD) patients have elevated biomarkers of inflammation. • There is a strong discrepancy between symptoms and biomarkers of inflammation in adults with IBD. What is New: • Clinical symptoms are only weakly associated with levels of fecal calprotectin and serum C-reactive protein in children and adolescents with previously diagnosed IBD. • Similarly to adult IBD patients, there is a strong discrepancy between clinical symptoms and biomarkers of inflammation in children with IBD.