Adhesive Bacteria in the Terminal Ileum of Children Correlates With Increasing Th17 Cell Activation

Bo Chen,Charlie Xiang,Weirong Liu,Lingling Luo,Diya Ye,Weizhong Gu,Xiaojun Wang,Kerong Peng,Xiaoli Shu,Mizu Jiang

doi:10.3389/fphar.2020.588560

Abstract

Humans and symbiotic bacteria are interdependent and co-evolved for millions of years. These bacteria communicate with human hosts in the gut in a contact-independent metabolite. Because most intestinal bacteria are non-adhesive, they do not penetrate the mucus layer and are not directly in contact with epithelial cells (ECs). Here, we found that there are adhesive bacteria attached to the Children's terminal ileum. And we compared the immune factors of non-adhesive bacteria in the children ileum with adhesive bacteria as well. Stimulated Th17 cell associated with adherent bacteria in the ileum ECs. SIgA responses are similar to those roles in mouse experiments. Immunohistochemical analysis confirmed that the expression of SAA1, IL-2, IL-17A, foxp3, RORγt, TGFβ, and protein increased in Th17 cells. Finally, we used 16S rRNA genes 454 pyrosequencing to analyze the differences in bacterial communities between adhesive and non-adhesive bacteria in the ileum. Ileum with adherent bacteria demonstrated increased mucosa-related bacteria, such as Clostridium, Ruminococcus, Veillonella, Butyricimonas, and Prevotella. We believe that adhesive bacteria in children’s terminal ileum associated with an increased Th17 cell activation and luminal secretory IgA. Adhesive bacteria very closely adhere to terminal ileum of children. They may play important role in human gut immunity and Crohn’s disease.

Highlights

Trillions of bacteria are present in our bodies (Sender et al, 2016)
Most ileum villi were without adhesive bacteria (Figures 1E–H). van der Waaij did not observe direct contact between bacterial and epithelial cells in adults with normal ileum mucosa
Among the 14 samples with collected adhesive bacteria, 12 samples were found in the ileum of children 11–36 months

Summary

Introduction

Trillions of bacteria are present in our bodies (Sender et al, 2016). These bacteria genomes encode a number of genes not naturally existing in the host, regulate host gut gene expression and affect the differentiation and maturation of the host immune system (Mazmanian et al, 2005). The intestinal walls in humans are joined between the luminal contents and the epithelium, and the mucus layer is separated from the gut bacteria in the intestinal epithelial cells (Meddings, 2008). The adhesion features of intestinal bacteria are key factors for inducing Th17 cells (Atarashi et al, 2015). One individual-based model demonstrated that hosts select specific bacteria using adhesion (McLoughlin et al, 2016), because adhesion provides a competitive advantage within host-associated communities

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Conclusion