Second-Generation Biomarker Testing for Irritable Bowel Syndrome Using Plasma Anti-CdtB and Anti-Vinculin Levels
ELISA testing for anti-CdtB and anti-vinculin can discriminate patients with irritable bowel syndrome with diarrhea (IBS-D) from those with inflammatory bowel disease (IBD). However, recent findings suggest the antigens can suffer from epitope instability.
This study aimed to assess effects of incorporating epitope stabilization on test characteristics for distinguishing IBS-D from IBD subjects.
Plasma samples from IBS-D subjects from a large-scale clinical trial and subjects with endoscopically active IBD without concurrent immunomodulator therapy were used. After epitope stabilization, CdtB and vinculin were used in ELISA testing. Optical density readings were compared between IBS-D and IBD subjects.
Samples from 100 IBS-D and 31 IBD (22 UC and 9 CD) subjects were tested. IBS-D subjects had higher anti-CdtB titers (P = 0.0001) and higher anti-vinculin titers (P = 0.004) than IBD subjects. The specificities of anti-CdtB and anti-vinculin to differentiate IBS-D from IBD were 93.5% and 90.9%, respectively, with sensitivities of 43.0% and 52.2%, respectively. The positive likelihood ratios of identifying IBS-D with anti-CdtB and anti-vinculin were 6.7 and 5.7, respectively. Assuming a pretest probability of 57% for diagnosis of IBS-D in patients with abdominal pain and change in bowel habits, testing positive for both antibodies resulted in a posttest probability of > 98%.
Performing epitope stabilization for CdtB and vinculin enhances the test characteristics of ELISAs for anti-CdtB and anti-vinculin in discriminating IBS-D from IBD. Measurement of anti-CdtB and anti-vinculin with this second-generation methodology may further advance our understanding of the role of immunity in functional bowel diseases.
KeywordsEpitope stabilization Cytolethal distending toxin Vinculin Enzyme-linked immunosorbent assay Diagnostic testing Irritable bowel syndrome
We would like to acknowledge Gemelli Biotech Inc and Pacific Dx (Irvine, California) for performing the sample analyses.
Compliance with ethical standards
Conflict of interest
Cedars-Sinai has a licensing agreement with Salix Pharmaceuticals and Gemelli Biotech. Mark Pimentel is a founder of Gemelli Biotech, has equity in the company, and serves on the board. Ali Rezaie is a founder of Gemelli Biotech and also has equity in the company. Walter Morales is a consultant for Gemelli Biotech. Gillian Barlow has no conflicts of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
- 2.Lovell RM, Ford AC. Global prevalence of and risk factors for irritable bowel syndrome: a meta-analysis. Clin Gastroenterol Hepatol. 2012;10:e714.Google Scholar
- 3.Mearin F, Lacy BE, Chang L, et al. Bowel disorders. Gastroenterology. 2016;150:1393–1407.Google Scholar
- 4.DA Drossman RJ, Talley NJ, et al. Functional gastrointestinal disorders: diagnosis, pathophysiology and treatment: a multinational consensus. Boston: Little, Brown; 1994.Google Scholar
- 7.American Gastroenterological Association. Guidelines–Rome III diagnostic criteria for functional gastrointestinal disorders. J Gastrointestin Liver Dis. 2006;15:307–312.Google Scholar
- 20.Klem F, Wadhwa A, Prokop LJ, et al. Prevalence, risk factors, and outcomes of irritable bowel syndrome after infectious enteritis: a systematic review and meta-analysis. Gastroenterology. 2017;152:e1041.Google Scholar
- 23.Parodi G, Morales W, Park SC, et al. Cytolethal distending toxin B (CdtB) exposure alone is sufficient to precipitate autoimmunity and changes to the small intestinal microbiome in a rat model of post-infectious IBS. Gastroenterology. 2017;152:S621.Google Scholar
- 29.Lombardero M, Heymann PW, Platts-Mills TA, Fox JW, Chapman MD. Conformational stability of B cell epitopes on group I and group II Dermatophagoides spp. allergens. Effect of thermal and chemical denaturation on the binding of murine IgG and human IgE antibodies. J Immunol. 1990;144:1353–1360.PubMedGoogle Scholar
- 33.American Gastroenterological Association. The burden of gastrointestinal diseases. Bethesda, MD: American Gastroenterological Association; 2001.Google Scholar