Dietary Gut Microbiota Perturbations Influence Murine Vaccine Response

The purpose of this study was to compare the effect of a tetanus vaccine on immunoglobulin G titers and immune cell levels in BALB/c mice fed either a gluten-free or a gluten containing diet and treated or not treated with ampicillin. The gluten-free diet lowered the initial titer response and thus produced more low responders, and it increased the abundance of the anti-inflammatory Bifidobacterium massively in some of the mice. Antibiotics similarly led to gut microbiota changes and lower initial titer without increasing low responder numbers. After boosting, neither gluten-free diet nor antibiotics influenced the titers. In the spleen, the gluten-free diet increased regulatory T cell (Treg) fractions, CD4+ T cell activation, and tolerogenic dendritic cell fractions and activation, which extend the downregulating effect of the Treg. Therefore, the systemic effect of the gluten-free diet seems mainly tolerogenic. Antibiotics reduced the fractions of CD4+ T and B cells in the mesenteric lymph nodes. Therefore, vaccine response in mice seems to be under influence of their diet, the gut microbiota and the interplay between them, although a gluten-free diet and antibiotics seems to work through different mechanisms. Therefore, both should be considered when testing vaccines in mice and developing vaccines for humans.