Potential urinary biomarkers of disease activity in Crohn's disease

Systematic Review: Urine Biomarker Discovery for Inflammatory Bowel Disease Diagnosis

Inflammatory bowel diseases (IBDs) are chronic, heterogeneous, and inflammatory conditions mainly affecting the gastrointestinal tract. Currently, endoscopy is the gold standard test for assessing mucosal activity and healing in clinical practice; however, it is a costly, time-consuming, invasive, and uncomfortable procedure for the patients. Therefore, there is an urgent need for sensitive, specific, fast and non-invasive biomarkers for the diagnosis of IBD in medical research. Urine is an excellent biofluid for discovering biomarkers because it is non-invasive to sample. In this review, we aimed to summarize proteomics and metabolomics studies performed in both animal models of IBD and humans that identify urinary biomarkers for IBD diagnosis. Future large-scale multi-omics studies should be conducted in collaboration with clinicians, researchers, and industry to make progress toward the development of sensitive and specific diagnostic biomarkers, thereby making personalized medicine possible.

Clinical Usefulness of Proteomics in Inflammatory Bowel Disease: A Comprehensive Review

The protein domain is probably the most ubiquitously affected in disease, response and recovery, and therefore proteomics holds special promise for biomarker discovery in general, and particularly in inflammatory bowel disease [IBD], i.e. ulcerative colitis and Crohn's disease. Tremendous progress has been made over the past decade in the development and refinement of proteomics technologies. These advances provide opportunities for a long-anticipated personalized medicine approach to the treatment of IBD. The present review examines the current state of IBD proteomics research and its usefulness in clinical practice. We performed a systematic bibliographic search to identify studies investigating the use of proteomics in patients with IBD, and we then summarized the current 'state of the art' in the applications of proteomic technologies in the study of IBD. In particular, in the present review we provide: [1] a brief introduction to proteomics in health and disease; [2] a review of the different stages from biomarker discovery to clinical application; and [3] a comprehensive review of the clinical usefulness and application of proteomics in IBD, including: [a] screening to differentiate IBD from healthy controls; [b] differentiating Crohn's disease from ulcerative colitis; [c] prediction of the behaviour or the IBD course; [d] prediction of IBD response to biological treatment; and [e] monitoring response to treatment. We also review the importance of the type of sample-blood vs intestinal tissue-for the study of proteomics in IBD patients. Finally, we emphasize the current limitations of proteomic studies in IBD.

Elevated urinary orosomucoid excretion as a novel biomarker in Crohn's disease

BACKGROUND

Laboratory markers are essential tools in the follow-up of patients with Crohn's disease (CD). Our aim was to investigate urinary concentrations of orosomucoid in relation to the inflammatory activity of CD and to compare it with clinical indices and conventional laboratory parameters.

MATERIALS AND METHODS

Blood and urine samples of 86 patients (55 adults and 31 children) with CD and 68 healthy individuals (38 adults and 30 children) as controls were analysed. Patients were categorized according to their clinical scores (Harvey-Bradshaw Index [HBI] or Pediatric Crohn's Disease Activity Index [PCDAI]). Urinary orosomucoid (u-ORM) was determined by automated immune turbidimetric assay, and values were referred to urinary creatinine (u-ORM/u-CREAT, mg/mmol).

RESULTS

U-ORM/u-CREAT values were seven times higher in children with active CD (0.50 vs 0.07 mg/mmol, P < 0.001) and two times higher in adults (0.32 vs 0.14 mg/mmol, P = 0.01) compared with patients with inactive disease. U-ORM/u-CREAT showed good correlation with conventional inflammatory markers (hs-CRP, serum ORM; P < 0.01) and activity indices (HBI, P = 0.018; PCDAI, P < 0.001). U-ORM/u-CREAT had similar discriminative performance to hs-CRP and serum ORM in the differentiation of active from inactive paediatric CD patients.

CONCLUSIONS

Our findings suggest that u-ORM/u-CREAT might serve as a valuable additional marker in the follow-up of CD patients, especially in children for whom the non-invasive sampling is a further advantage.

Role of biomarkers in diagnosis and evaluation of disease activity of Crohn's disease

Crohn's disease (CD) is a group of chronic, relapsing inflammatory gastrointestinal diseases with unknown etiology. The goals of treatment are to induce the transition from active stage into inactive stage and to maintain remission. Therefore, it is important to diagnose and assess disease activity in patients with CD. Recently, noninvasive markers for intestinal inflammation have been wildly adopted in clinical practice in order to differentiate CD from other diseases, to grade inflammation, to assess the response to therapy, and to demonstrate recurrent inflammation after medical or surgically-induced remission. Fecal and serum calprotectins are among the best-studied noninvasive biomarkers of inflammation in CD which have attracted clinicians' attention. This paper gives an overview of the clinical implications of biomarkers for diagnosing and monitoring disease activity of CD.

Biomarkers of Inflammation in Inflammatory Bowel Disease

Recent observations suggest that subjective measures of disease activity in inflammatory bowel disease (IBD) are often misleading. Objective measures of inflammation are more closely associated with important long-term outcomes, but often depend upon invasive and costly procedures such as ileocolonoscopy and cross-sectional imaging by computed tomography or magnetic resonance imaging. Noninvasive, accurate, and inexpensive measures of intestinal inflammation would allow clinicians to adopt widely the paradigm of adjusting therapies with a goal of controlling inflammation. Blood, stool, and urine markers have all been explored as indicators of intestinal inflammation in IBD, and although none has been universally adopted, some have been well-characterized, and others hold great promise. Serum C-reactive protein and fecal calprotectin are among the best-studied noninvasive biomarkers of inflammation in IBD, and their test characteristics have been described in the setting of differentiating IBD from irritable bowel syndrome, for grading inflammation, to describe the response to therapy, and in demonstrating recurrent inflammation after medical or surgically induced remission. High-throughput research platforms, including gene expression arrays, metabolomics and proteomics, are also being applied to the discovery of novel biomarkers of inflammation. It is certain that biomarkers of inflammation will attain growing importance in the clinic as we strive for more effective and cost-effective strategies to treat patients with IBD.

Current advantages in the application of proteomics in inflammatory bowel disease

Since the formulation of the concept of proteomics, a plethora of proteomic technologies have been developed in order to study proteomes. In inflammatory bowel disease (IBD), several studies use proteomics to try to better understand the disease and discover molecules which can be used as biomarkers. Biomarkers should be able to be used for diagnosis, therapy and prognosis. Although several biomarkers have been discovered, few biomarkers have clinical value. In this review, we analyze and report the current use of proteomic techniques to highlight biomarkers characterizing IBD, and different stages of disease activity. We also report the biomarkers and their potential clinical value.

Immunochemically unreactive albumin in urine: fiction or reality?

Urinary albumin measurements are currently not standardized due to a lack of a reference method and reference (primary and secondary [matrix]) material. Multiple molecular forms of albumin in urine are identified. Modification of albumin by proteolysis during passage through the urinary tract and chemical modification during specimen storage leads to the formation of albumin fragments. Multiple methods have been developed to quantify albuminuria and significant different results are reported dependent on the available assay. The current point of view of the National Kidney Disease Education Program - IFCC Working Group on Standardization of Albumin considers the immunoassay with polyclonal sera as the primary method of quantifying urine albumin. This article reviews the process of albumin fragmentation and focuses on the controversial topic of immuno-unreactive, nonimmunoreactive, or immunochemically nonreactive albumin fractions and its consequences for albumin analysis. We conclude that at present there are no hard arguments for measuring immunochemically unreactive albumin in urine. Immunoassays using polyclonal antisera for the detection of urinary albumin remain the gold standard. The development of a reference measurement procedure remains one of the challenges for the future.