Abstract
Probiotics make up a large and growing segment of the commercial market of dietary supplements and are touted as offering a variety of human health benefits. Some of the purported positive impacts of probiotics include, but are not limited to, stabilization of the gut microbiota, prevention of gastrointestinal disorders and modulation of the host immune system. Current research suggests that the immunomodulatory effects of probiotics are strain-specific and vary in mode of action. Here, we examined the immunomodulatory properties of Bacillus subtilis strain DE111 in a healthy human population. In a pilot randomized, double blind, placebo-controlled four-week intervention, we examined peripheral blood mononuclear cells (PBMCs) at basal levels pre- and post-intervention, as well as in response to stimulation with bacterial lipopolysaccharide (LPS). We observed an increase in anti-inflammatory immune cell populations in response to ex vivo LPS stimulation of PBMCs in the DE111 intervention group. Overall perceived gastrointestinal health, microbiota, and circulating and fecal markers of inflammation (Il-6, sIgA) and gut barrier function (plasma zonulin) were largely unaffected by DE111 intervention, although the study may have been underpowered to detect these differences. These pilot data provide information and justification to conduct an appropriately powered clinical study to further examine the immunomodulatory potential of B. subtilis DE111 in human populations.
Highlights
The human GI tract houses roughly 3.8 × 1013 microorganisms comprising up to 1000 different species [1]
Spore-forming Bacillus subtilis is becoming increasingly popular as a probiotic supplement due to its enhanced shelf life and survivability in the human digestive tract relative to other bacterial species
The in vivo viability, safety, and tolerability of several strains of B. subtilis have been assessed in appropriate human populations [17,18,19,20], little is known about other specific benefits these bacteria may convey
Summary
The human GI tract houses roughly 3.8 × 1013 microorganisms comprising up to 1000 different species [1]. Studies of the interactions between the microbiota and immune cells reveal various immune-modulatory mechanisms, including activation of innate and humoral cell populations, induction of cytokine production, stimulation of secretory IgA production, competitive exclusion of pathogenic bacteria, and generation of bioactive metabolites, such as short chain fatty acids (SCFA) [5,6,7,8]. These interactions have led to the commercialization of probiotic organisms to promote immune health in consumers
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