Safety and immunomodulatory effects of three probiotic strains isolated from the feces of breast-fed infants in healthy adults: SETOPROB study

Abstract

We previously described the isolation and characterization of three probiotic strains from the feces of exclusively breast-fed newborn infants: Lactobacillus paracasei CNCM I-4034, Bifidobacterium breve CNCM I-4035 and Lactobacillus rhamnosus CNCM I-4036. These strains were shown to adhere to intestinal mucus in vitro, to be sensitive to antibiotics and to resist biliary salts and low pH. In the present study, a multicenter, randomized, double-blind, placebo-controlled trial with 100 healthy volunteers in three Spanish cities was carried out to evaluate the tolerance, safety, gut colonization and immunomodulatory effects of these three probiotics. Volunteers underwent a 15-day washout period, after which they were randomly divided into 5 groups that received daily a placebo, a capsule containing one of the 3 strains or a capsule containing a mixture of two strains for 30 days. The intervention was followed by another 15-day washout period. Patients did not consume fermented milk for the entire duration of the study. Gastrointestinal symptoms, defecation frequency and stool consistency were not altered by probiotic intake. No relevant changes in blood and serum, as well as no adverse events occurred during or after treatment. Probiotic administration slightly modified bacterial populations in the volunteers' feces. Intestinal persistence occurred in volunteers who received L. rhamnosus CNCM I-4036. Administration of B. breve CNCM I-4035 resulted in a significant increase in fecal secretory IgA content. IL-4 and IL-10 increased, whereas IL-12 decreased in the serum of volunteers treated with any of the three strains. These results demonstrate that the consumption of these three bacterial strains was safe and exerted varying degrees of immunomodulatory effects.

Trial registration: ClinicalTrials.gov NCT01479543.

Conflict of interest statement

Competing Interests: Part of the research currently in progress in the authors' laboratory is funded by the company Hero Spain, S. A. through the grant #3582 managed by the Fundacion General Empresa-Universidad de Granada. EM, IO, RMS and FR are employed by Hero Global Technology Center, Hero Spain, S.A. This center is part of the food company HERO, headquartered in Switzerland. EC, SG, BC, AS and DR are employed by Biopolis S.L., a spin-off of the Cover Letter National Spanish Research Council (Consejo Superior de Investigaciones Científicas), Ministry of Education, Spain. There are no patents, products in development or marketed products to declare. This does not alter the authors' adherence to all the PLOS ONE policies on sharing data and materials, as detailed online in the guide for authors.

Figures

Figure 1. CONSORT flow diagram of the subjects in the SETOPROB study (NCT01479543).

Figure 2. Secretory IgA content (A) and populations of Clostridium difficile (B), Bacteroides (C), Lactobacillus (D), and Bifidobacterium spp. (E) in the feces of healthy adults fed one daily probiotic capsule or placebo for 4 weeks as log CFU/g feces.

Values are means ± SEM, n=20 per group. Labeled means without a common letter differ, P<0.05. Time 1, first washout; Time 2, intervention; Time 3, second washout.

Figure 3. Serum IL-4 (A), IL-10 (B), and IL-12 (C) concentrations and IL-10/TNF-α (D), and IL-10/IL-12 ratios (E) in healthy adults fed one daily capsule of probiotics or placebo for 4 weeks.

Values are means ± SEM, n=20 per group. Labeled means without a common letter differ, P<0.05. Time 1, first washout; Time 2, intervention.