Metabolism of Dietary and Microbial Vitamin B Family in the Regulation of Host Immunity.

Ken Yoshii,Koji Hosomi,Kento Sawane,Jun Kunisawa

doi:10.3389/fnut.2019.00048

Abstract

Vitamins are micronutrients that have physiological effects on various biological responses, including host immunity. Therefore, vitamin deficiency leads to increased risk of developing infectious, allergic, and inflammatory diseases. Since B vitamins are synthesized by plants, yeasts, and bacteria, but not by mammals, mammals must acquire B vitamins from dietary or microbial sources, such as the intestinal microbiota. Similarly, some intestinal bacteria are unable to synthesize B vitamins and must acquire them from the host diet or from other intestinal bacteria for their growth and survival. This suggests that the composition and function of the intestinal microbiota may affect host B vitamin usage and, by extension, host immunity. Here, we review the immunological functions of B vitamins and their metabolism by intestinal bacteria with respect to the control of host immunity.

Highlights

The gut is continuously exposed both to toxic and beneficial compounds and microorganisms; the intestinal immune system must maintain a healthy balance between active and suppressive immune responses
Metagenomic analysis has predicted that Bacteroides fragilis and Prevotella copri (Bacteroidetes); Clostridium difficile, Faecalibacterium prausnitzii and Ruminococcus lactaris (Firmicutes); Bifidobacterium animalis, B.infantis, and B.longum (Actinobacteria); Fusobacterium varium (Fusobacteria) possess a vitamin B12 biosynthesis pathway
B-vitamin-mediated immunological regulation is specific to different immune cells and immune responses: that is, different B vitamins are required for different immune responses (Figure 4)

Summary

Introduction

The gut is continuously exposed both to toxic (e.g., pathogenic microorganisms) and beneficial (e.g., dietary components, commensal bacteria) compounds and microorganisms; the intestinal immune system must maintain a healthy balance between active and suppressive immune responses. A metagenome analysis of the human gut microbiota by Magnúsdóttir et al [10] has predicted that Bacteroides fragilis and Prevotella copri (Bacteroidetes); Clostridium difficile, Lactobacillus plantarum, L. fermentum, and Ruminococcus lactaris (Firmicutes) express factors essential for vitamin B2 synthesis, suggesting that these bacteria are an important source of vitamin B2 in the large intestine (Table 1). Bacteroides fragilis and Prevotella copri (Bacteroidetes); Ruminococcus lactaris, Clostridium difficile (Firmicutes); Bifidobacterium infantis (Actinobacteria); Helicobacter pylori (Proteobacteria); and Fusobacterium varium (Fusobacteria) possess a vitamin B3 biosynthesis pathway (Table 1) [10, 71].

Results

Conclusion