Clinical significance of soluble immunoglobulins A and G and their coated bacteria in feces of patients with inflammatory bowel disease

Ritian Lin,Zhi Pang,Weigang Shu,Leilei Fang,Mingming Sun,Hongwei Chen,Yanhong Shi,Zhanju Liu,Wei Wu

doi:10.1186/s12967-018-1723-0

Abstract

BackgroundImmunoglobulin A (IgA) and IgG are major components in human intestinal mucosal surface and sera, and IgA- or IgG-coated bacteria play a vital role in the intestinal homeostasis. However, the correlation of IgA, IgG and their coated bacteria with the clinical characteristics of inflammatory bowel disease (IBD) has not been fully clarified.MethodsThe levels of soluble IgA and IgG in sera and feces were detected by ELISA, and the percentage of IgA- and IgG-coated bacteria in feces was analyzed by flow cytometry. Crohn’s disease activity index (CDAI) and Simple Endoscopic Score for Crohn’s disease (SES-CD) for Crohn’s disease (CD) or Mayo score and ulcerative colitis endoscopic index of severity (UCEIS) for ulcerative colitis (UC), erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were used to evaluate the disease activity.Results178 patients with CD, 75 patients with UC and 41 healthy donors were recruited in this study. We found that the concentrations of soluble IgA and IgG in feces of active IBD patients were significantly higher than those in healthy controls and that the levels of soluble IgA and IgG in feces from IBD patients were positively correlated with CRP, ESR, Mayo score, UCEIS, SES-CD, and CDAI, respectively. Moreover, we also observed that the percentage of IgA- and IgG-coated bacteria markedly increased in feces of IBD patients, especially in CD patients at the age of 17 to 40 years old, with terminal ileal lesions and perianal lesions, as well as from E2 UC patients, and was closely associated with disease activities.ConclusionsThe levels of soluble IgA and IgG and the percentage of IgA- and IgG-coated bacteria strikingly increase in feces of IBD patients and correlate with disease activity.

Highlights

Immunoglobulin A (IgA) and immunoglobulin G (IgG) are major components in human intestinal mucosal surface and sera, and IgA- or IgG-coated bacteria play a vital role in the intestinal homeostasis
These data indicate that soluble IgA and IgG are conspicuously up-regulated in feces of active inflammatory bowel disease (IBD) patients
Fecal soluble IgA and IgG are positively correlated with the disease activity of Crohn’s disease (CD) To further investigate the clinical implication of the concentrations of fecal IgA and IgG, we analyzed the disease behaviors in CD patients according to the Montreal classification

Summary

Introduction

Immunoglobulin A (IgA) and IgG are major components in human intestinal mucosal surface and sera, and IgA- or IgG-coated bacteria play a vital role in the intestinal homeostasis. It is believed that intestinal infections, epithelial barrier disruption, dysregulated mucosal immune response to commensal microbiota and genetic variation are involved in the pathogenesis of IBD [3, 4]. Both innate immune response and adaptive immune response are found to play a vital role in the development of intestinal mucosal inflammatory damage [5,6,7]. The disease surveillance includes CRP, ESR, CDAI, SESCD, UCEIS, and Mayo score. The rise of CRP or ESR in blood refers to acute inflammation, while CDAI and Mayo scores relies on clinical evaluation by physicians. Several invasive methods such as blood biochemical tests and endoscopic examination have been used in the clinic, novel non-invasive disease activity-monitoring techniques are needed to replace the existing techniques

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Conclusion