Fecal Microbiota Transplantation Enhances Phagocytic Activity and T-cells Immunity Mediated by Bacterial Vaccines

Faecal microbiota transplantation is a next-generation medical therapy for several clinical issues. However, the effect of this approach has not been studied in the context of vaccination. Here, we aimed to use Faecal microbiota transplantation as an adjuvant to enhance both phagocytic activity and T-cells immunity in response to bacterial vaccination. 20 albino mice (5 groups, 4 mice per group) were used in this study. Two groups were subjected to Faecal microbiota transplantation with 100 µl of faecal slurry from a healthy adult via two routes (with and without gut microbiota modulation by a cocktail of antibiotics), then immunized with 100 µg of bacterial vaccine. The remaining groups were the control group treated with PBS, the bacterial vaccine alone immunized group, and the PLGA-encapsulated bacterial vaccine immunized group.

The results clearly show that the phagocytic activity of macrophages increased significantly to (74.67±6.11) % in vaccinated mice after Faecal microbiota transplantation with modulation of gut microbiota group compared to both the control group (38.67±2.31) % and vaccinated mice after Faecal microbiota transplantation without modulation of gut microbiota (57.33±6.11). Also, PLGA-encapsulated bacterial vaccine increases phagocytic activity by 62.67±8.33%. Only those vaccinated mice after Faecal microbiota transplantation with modulation of gut microbiota showed a significant increase in levels of delayed-type hypersensitivity, with 2.5±0.71 mm compared to 0.25±0.35 mm in the control group. Overall, enhanced cellular immunity in response to the bacterial vaccine after Faecal microbiota transplantation, with modulation of the gut microbiota, suggests that this approach is a promising next-generation bacterial adjuvant.