ASCA, ANCA, ALCA and Many More: Are They Useful in the Diagnosis of Inflammatory Bowel Disease?

Background: Inflammatory bowel disease (IBD) is characterized by excessive immune responses to altered intestinal microbiota in genetically susceptible individuals. The diagnosis of IBD depends on clinical, endoscopic, histological, radiological and biochemical criteria, which may be invasive, time consuming and usually not accepted by patients with IBD. Key Messages: Serological biomarkers have been demonstrated to be a series of rapid, non-invasive approaches for assessments of early diagnosis, disease activity and prognosis for IBD. Importantly, serum antibodies against microbial antigens or auto-antigens have been used as biomarkers in predicting disease course, complications and responses to medications and surgery. Moreover, they have been demonstrated to be useful in distinguishing patients with Crohn's disease (CD) from those with ulcerative colitis (UC). Recently, a great number of new serum biomarkers (e.g., anti-glycoprotein 2, anti-granulocyte macrophage colony-stimulating factor, anti-neutrophil cytoplasmic antibody, anti-Saccharomyces cerevisiae antibody, anti-laminaribioside carbohydrate IgG antibody, anti-mannobioside carbohydrate IgG antibody, antibody to the outer membrane protein of Escherichia coli, anti-CBir1) have been found to be present in patients with IBD and are potentially used in the diagnosis and prediction. The presence of these antibodies in the sera is due to the disruption of intestinal mucosa barrier and they may reflect a possibly genetic loss of immunological tolerance toward microbiota-derived antigens. Due to their non-invasive, easily accessible, repetitive and economical characteristics, these biomarkers have been found to serve as precious supplementary means in the diagnosis and disease evaluation of IBD. Conclusions: Currently, the most important utility of serological biomarkers is to evaluate the aggressive risks of disease phenotype, complications or surgery requirement, predict prognosis of the disease and distinguish CD from UC. However, they have limited values in making initially definite diagnosis for IBD. Therefore, more effective biomarkers with high sensitivity and specificity need to be further explored in the future.