The Cross Talk Between the Immune System and the Gut Microbiota

Introduction

Both the immune system and the gut microbiota are complex systems composed of multiple cell types (or organisms), interacting closely by molecules produced by both entities. It is clear that these interactions affect the host state and immune system development, some signaling molecules have been reported, however, the mechanisms of these communications are mostly unknown. Here we aim to study the importance and the mechanisms by which the immune system influences the microbiota, and in turn, the reciprocal influence of the microbiota on the immune system.

Methods

We used a mouse model that allows us to externally manipulate the regulatory T cells (Tregs) population. We performed fecal microbiota transplant (FMT) to test the effects of the microbial composition on the immune system. Immunophenotyping was monitored by flow cytometry, and the bacterial composition was characterized by sequencing.

Results

We observed a shift in the immune cell population following ablation of Tregs. We also detected changes in the immune system following different FMT treatments. Bacterial composition was found to remain mostly stable throughout the experiment.

In addition, we detected elevation in antibodies to diet components in the treated mice, these antibodies changed in correlation to the FMT treatments.

Conclusions

We demonstrated that the immune system and the microbiota affect each other in a feedback manner. This cross talk might be mitigated by bacterial functionality rather than composition. Studying the intricate interplay between the microbiota and the immune system may allow to design and develop future clinical diagnostics and therapeutic interventions.