Serum Biomarkers for Inflammatory Bowel Disease

Abstract

Background: Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is a chronic, inflammatory disorder of the gastrointestinal tract. As the novel therapeutic goal and biologicals are widely recognized, accurate assessment of disease and prediction of therapeutic response have become a crucial challenge in clinical practice. Also, because of the continuously rising incidence, convenient and economical methods of diagnosis and clinical assessment are urgently needed. Recently, serum biomarkers have made a great progress and become a focus in IBD study because they are non-invasive, convenient, and relatively inexpensive than are markers in biopsy tissue, stool, breath, and other body fluids. Aims: To review the available data on serological biomarkers for IBD. Methods: We searched PubMed using predefined key words on relevant literatures of serum biomarkers regarding diagnosis, evaluation of therapeutic efficacy, surveillance of disease activity, and assessment of prognosis for IBD. Results: We reviewed serological biomarkers that are well-established and widely used (e.g., C-reactive protein), newly discovered biomarkers (e.g., cytokines, antibodies, and non-coding RNAs), and also recently advancements in serological biomarkers (e.g., metabolomics and proteomics) that are used in different aspects of IBD management. Conclusions: With such a wealth of researches, to date, there are still no ideal serum biomarkers for IBD. Serum profiling and non-coding RNAs are just starting to blossom but reveal great promise for future clinical practice. Combining different biomarkers can be valuable in improving performance of disease evaluation.

Keywords: C-reactive protein; Inflammatory bowel disease; Serum biomarker; activity evaluation; diagnosis; non-coding RNA; prognosis prediction.

Figure 1

Serum biomarkers for inflammatory bowel disease (IBD) management. Antimicrobial antibodies are antibodies that targeted microbiota-derived antigens through the interplay between host immune system and gut microbiota. Both environmental factors and gut microbiota influence metabolome of patients. Patients with IBD tend to show a low level of vitamin D, which is partly caused by absorption dysfunction due to active disease. Intestinal epithelial cells from the inflamed mucosa secrete exosome, which contains microRNA (miRNAs) and long non-coding RNAs (lncRNAs) and other functional proteins in circulation. Pro-inflammatory cytokines were secreted by activated immune cells, which induce the expression of CRP. Excessive deposition of extracellular matrix (ECM) components include laminin, fibronectin, collagen, and its propeptide. Several growth factors mediating development of fibrostenosis [platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), and YKL-40]. bFGF promotes tissue healing by regulating proliferation of myofibroblast. Transforming growth factor (TGF)-β induced the expression of collagen and promoted intestinal fibrosis through inhibiting the expression of miR-29.