Cutting Edge: Probiotics and Fecal Microbiota Transplantation in Immunomodulation

Abstract

Probiotics are commensal or nonpathogenic microbes that confer beneficial effects on the host through several mechanisms such as competitive exclusion, antibacterial effects, and modulation of immune responses. Some probiotics have been found to regulate immune responses via immune regulatory mechanisms. T regulatory (Treg) cells, T helper cell balances, dendritic cells, macrophages, B cells, and natural killer (NK) cells can be considered as the most determinant dysregulated mediators in immunomodulatory status. Recently, fecal microbiota transplantation (FMT) has been defined as the transfer of distal gut microbial communities from a healthy individual to a patient's intestinal tract to cure some immune disorders (mainly inflammatory bowel diseases). The aim of this review was followed through the recent literature survey on immunomodulatory effects and mechanisms of probiotics and FMT and also efficacy and safety of probiotics and FMT in clinical trials and applications.

Figure 1

The dual functions of probiotics on the immune system in in vitro and animal experiments. ↑: activity enhanced or quantity increased; ↓: activity reduced or quantity decreased. Immune cell: immune cells on which probiotics directly stimulate. Effects: the immunological effect generated by immune cells stimulated by probiotics, mainly including the regulation on cytokines and the differentiation of related immune cell subpopulations.

Figure 2

Effects of probiotics on the Th17/Treg balance. Treg can be increased by probiotics, such as Lactobacillus (plantarum, fermentum, salivarius, acidophilus, casei, and rhamnosus), Bifidobacterium (animalis, infantis, longum, lactis, and breve), and Bacillus coagulans, Clostridium butyricum, Weissella cibaria, Enterococcus durans, and Prevotella histicola. Th17 can be increased by probiotics, such as Lactobacillus plantarum, Bifidobacterium adolescentis. Conversely, Th17 can be decreased by probiotics, such as Lactobacillus (delbrueckii, acidophilus, and rhamnosus), Bifidobacterium breve, and Enterococcus faecalis and Prevotella histicola.