Vibrio parahaemolyticus Infection in Mice Reduces Protective Gut Microbiota, Augmenting Disease Pathways

Abstract

Vibrio parahaemolyticus (Vp), a major food-borne pathogen, is responsible for severe infections such as gastroenteritis and septicemia, which may be accompanied by life-threatening complications. While studies have evaluated factors that affect the virulence of the pathogen, none have investigated the interaction of Vp with gut microbiota. To address this knowledge gap, we compared the effect of Vp on gut bacterial community structure, immunity, liver and kidney function, in pseudo germ-free (PGF) mice and normal (control) mice. Significant damage to the ileum was observed in normal mice compared with the PGF mice. The inflammatory factors IL-1β, IL-6, and TNF-α in normal mice were ∼2.5-fold higher than in the PGF mice, and liver (ALT, AST, ALP) and kidney (BUN) function indices were ∼1.6-fold higher. The Vp infection substantially reduced species composition and richness of the gut microbial communities. In particular, there was a shift in keystone taxa, from protective species of genera Bacteroides, Lactobacillus, Bifidobacterium, and Akkermansia in the gut of control mice to opportunistic pathogens Enterobacteriaceae, Proteus, Prevotella, and Sutterella in Vp-infected mice, thus affecting microbiota-related biological functions in the mice. Specifically, pathways involved in infectious diseases and ion channels were significantly augmented in infected mice, while the pathways involved in metabolism, digestion and cell growth declined. We propose that the normal mice are more prone to Vp infection because of the alteration in gut-microbe-mediated functions. All these effects reduce intestinal resistance, with marked damage to the gut lining and pathogen leakage into the blood culminating in liver and kidney damage. These findings greatly advance our understanding of the mechanisms underlying interactions between Vp, the gut microbiota and the infected host.

Keywords: 16S rRNA gene; Vibrio parahaemolyticus infection; gene sequencing; gut microbiota; pathogenesis.

FIGURE 1

Effects of oral gavage with Vibrio parahaemolyticus (Vp) on the ileum of pseudo germ-free and normal (SPF) mice. (A) Pseudo germ-free mouse, (B) SPF mouse, (C) control mouse. The control mice were given fresh sterilized LB medium instead of Vp.

FIGURE 2

Effects of Vibrio parahaemolyticus on serum AST, ALT, ALP, and BUN indices of pseudo germ-free (PGF) and normal (SPF) mice. Data are expressed as the mean ± SEM (n = 5) compared with the control group gavaged with fresh sterilized LB medium. *p < 0.05; **p < 0.01.

FIGURE 3

Effects of Vibrio parahaemolyticus on the serum IL-1β, IL-6, TNF-α, and IL-10 indices of pseudo germ-free mice and normal mice. Data are expressed as the mean ± SEM (n = 5) compared with the control group gavaged with fresh sterilized LB medium. *p < 0.05; **p < 0.01.

FIGURE 4

Vibrio parahaemolyticus-induced gut microbiota dysbiosis. (A) Venn diagram analysis of unique/shared OTUs in the gut microbiota of experimental mice following V. parahaemolyticus (Vp) infection. (B,C) The ileum microbiome composition profiles at the phylum and genus level in the control group and Vp-infected groups (each color represents one bacterial taxon). (D) UniFrac principal co-ordinates analysis estimates of ileum microbiota in the control and Vp-infected groups.

FIGURE 5

Identification of significant differences in bacterial taxa between Vp-infected and control groups. Cladogram shows the differences and phylogenic location. In each section, the diameter of the circle is proportional to the abundance of the taxon. Ileum microbial communities from Vp-infected and control mice were compared using LEfSe (red = taxon significantly enriched in control; green = taxon significantly enriched in Vp-infected; yellow = not-significant). Histogram of the LDA scores computed for features differentially abundant between the Vp-infected and control groups. LEfSe scores represent the degree of consistent difference in relative abundance between features in two groups of analyzed microbial communities. The clades of the histogram identify statistical and biological differences between the communities. Taxonomic groups showing LDA scores >2.0 with p < 0.05.

FIGURE 6

Predicted KEGG pathways of mice gut microbiota. Changes in the abundance of KEGG metabolic pathways in the Vp-infected group relative to the control group at 12 h. The red color intensity indicates the richness of metabolic pathways.