Probiotic-induced changes in intestinal microbiome inhibits Toxoplasma gondii infection

Abstract

Toxoplasma gondii primarily invades the central nervous system, causing latent infections. Cysts persist in the host for life and there is currently no effective treatment. T. gondii infects human hosts through contaminated meat, invading the intestinal tissue and leading to changes in the number and composition of the gut microbiota. Since probiotic ingestion modulates intestinal microbiota changes, we hypothesized that intestinal microbiota dysbiosis caused by T. gondii infection would be restored following probiotic supplementation. To this end, we orally infected C57BL/6 mice with 10 T. gondii cysts and administered supplemental probiotics daily. We analyzed the levels of T. gondii B1 gene DNA, indicative of T. gondii infection, in brain tissue. We investigated alterations in the gut microbiota composition and functional pathways between the probiotic and non-probiotic treatment groups via next-generation sequencing analysis of each fecal sample. The infection level in the probiotic-treated group was significantly reduced after 4 weeks (p<0.05). Probiotic supplementation notably changed the gut microbiota after 2 weeks of infection, increasing the relative abundance of Intestinimonas massiliensis and Lawsonibacter asaccharolyticus. Probiotic supplements appear to modulate the gut microbiota, activating functional pathways involved in intestinal short-chain fatty acid production and strengthening the intestinal barrier, thereby impeding T. gondii infection and subsequent proliferation. Our findings provide valuable insights into T. gondii infection control and future study directions.

Keywords: Toxoplasma gondii; microbiota; next-generation sequencing; probiotics.

Fig. 1

Level of B1 gene DNA in Toxoplasma gondii-infected mice. The T. gondii-specific B1 gene was used as a marker to assess the extent of T. gondii infection. Bars represent fold changes in B1 gene DNA compared with the control. Control, uninfected group; Tg, T. gondii-infected group; Tg+PB, T. gondii-infected group receiving probiotic supplementation. *P<0.05 compared with the control group, ^†P<0.05 between groups.

Fig. 2

Comprehensive analysis of microbial community composition and diversity across taxonomic levels. (A) Bar graph of the relative abundance of microbial communities at the phylum level. (B) Bar graph of the microbial community composition at the genus level. (C) Microbial diversity analysis of fecal samples. The observed species, Chao1, and Shannon indices reflect species abundance. richness, and evenness, respectively. (D) Venn diagrams of shared and unique microbial taxa at the genus and species levels in fecal samples. Numbers in each section of the circle represent the number of taxa shared or unique to the group.

Fig. 3

Comparative analysis of microbial community changes. (A) PCoA results of microbial communities based on weighted UniFrac distances across different treatment groups and time points. ANOSIM was used to determine the statistical significance of differences between groups. (B) PCoA results of microbial communities based on unweighted UniFrac distances (C). Graph presenting the results of a LEfSe analysis performed to identify statistically significant differences in the microbial taxa across the control, Tg, and Tg+PB groups after 2 and 4 weeks of Toxoplasma gondii infection. Each bar represents a significantly enriched microbial taxon in one of the groups. Bar length indicates the extent of the difference.

Fig. 4

LEfSe analysis of microbial differences between the Tg and Tg + PB groups after 2 weeks of infection with Toxoplasma gondii. (A) Bar graph showing the results of the LEfSe analysis performed to determine significant differences in microbial species between the Tg and Tg+PB groups after 2 weeks of infection with Toxoplasma gondii. (B) Boxplot showing the substantial increase in Intestinimonas massiliensis and Lawsonibacter asaccharolyticus in the Tg+PB group after 2 weeks of infection.

Fig. 5

Heatmap of pathway abundance scores in gut microbiota influenced by probiotic supplementation during Toxoplasma gondii infection. The heatmap is a visual representation of functional changes in the gut microbiota induced by probiotic supplementation after 2 weeks of T. gondii infection in mice. Pathway abundance scores derived from PICRUSt2 analysis highlight critical functional changes in microbial metabolism.