Isolation and Characterization of New Probiotic Strains From Chinese Babies.

GOALS: The aims of this study were to isolate, to identify, and to characterize new potential probiotic strains from the feces of Chinese neonates. BACKGROUND: Probiotic strains approved in China for use in infants were declared to originate from the human gut of Western subjects. Diet is listed among the main factors affecting the composition of the human gut along with other factors such as genetics, lifestyle, and health status. On the basis of this, the lifestyle of mothers, including dietary habits, could have an impact on the bacterial strains that colonize the gut of their babies. STUDY: Starting from fecal samples, plated onto selective media, of 26 babies, a total of 38 Lactobacillus and 45 Bifidobacterium colonies were isolated and subcultured, identified at the specie level with the partial sequencing of the 16S ribosomal RNA gene, and assessed for safety according to international guidelines for probiotics and European guidance. Only 6 Lactobacillus and 5 Bifidobacterium spp. were included for further analysis for the evaluation of survival rate within the gastrointestinal tract and for adhesive properties on the Caco-2 cell line. Some tests for prebiotic metabolism and growth on reconstituted skimmed milk were also performed. RESULTS: Three Lactobacillus strains and 1 Bifidobacterium strain showing interesting adhesive abilities were included in the in vitro immune-stimulatory test with dendritic cells. Among these isolates, the Bifidobacterium breve 2TA showed the most interesting probiotic properties. CONCLUSIONS: The results obtained led to the identification of 4 new potential probiotic strains from Chinese babies to be submitted to further investigations about their metabolic and functional features.

Collaborative cytometric inter-laboratory ring test for probiotics quantification.

Introduction: Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. From this definition, accurate enumeration of probiotic products is a necessity. Nonetheless, this definition does not specify the methods for assessing such viability. Colony forming units is the de facto gold standard for enumerating viable in probiotic products. The notion of microbial viability has been anchored in the concept of cultivability, which refers to a cell's capacity to replicate and form colonies on agar media. However, there is a growing consensus that the term "viability" should not be exclusively tied to the ability to cultivate cells. For example, bacterial cells can exist in a Viable But Non-Culturable (VBNC) state, characterized by the maintenance of characteristics such as membrane integrity, enzymatic activity, pH gradients, and elevated levels of rRNA, despite losing the ability to form colonies. Methods: Herein we present the results of a collaborative inter-laboratory ring test for cytometric bacterial quantification. Specifically, membrane integrity fluorescence flow cytometry (FFC) method and the newer impedance flow cytometry (IFC) method have been used. Both methods interrogate single cells in solution for the presence of intact membranes. FFC exploits fluorochromes that reflect the presence or absence of an intact membrane. IFC probes membrane integrity in a label-free approach by detecting membrane-induced hindrances to the propagation of electricity. Results: A performance ring-test and comparison design on the FFC method showed that the method is robust against the exchange of equipment, procedures, materials, and operators. After initial method optimization with assessments of rehydration medium, wake-up duration, and phase shift gating on the individual strains, the IFC method showed good agreement with the FFC results. Specifically, we tested 6 distinct species of probiotic bacteria (3 Lactobacillus and 3 Bifidobacterium strains) finding good agreement between FFC and IFC results in terms of total and live cells. Discussion: Together, these results demonstrate that flow cytometry is a reliable, precise, and user-friendly culture-independent method for bacterial enumeration.

Gut microbiota and probiotics: novel immune system modulators in myasthenia gravis?

Gut microorganisms (microbiota) live in symbiosis with the host and influence human nutrition, metabolism, physiology, and immune development and function. The microbiota prevents pathogen infection to the host, and in turn the host provides a niche for survival. The alteration of gut bacteria composition (dysbiosis) could contribute to the development of immune-mediated diseases by influencing the immune system activation and driving the pro- and anti-inflammatory responses in order to promote or counteract immune reactions. Probiotics are nonpathogenic microorganisms able to interact with the gut microbiota and provide health benefits; their use has recently been exploited to dampen immunological response in several experimental models of autoimmune diseases. Here, we focus on the relationships among commensal bacteria, probiotics, and the gut, describing the main interactions occurring with the immune system and recent data supporting the clinical efficacy of probiotic administration in rheumatoid arthritis, multiple sclerosis, and myasthenia gravis (MG) animal models. The encouraging results suggest that selected strains of probiotics should be evaluated in clinical trials as adjuvant therapy to restore the disrupted tolerance in myasthenia gravis.

Administration of bifidobacterium and lactobacillus strains modulates experimental myasthenia gravis and experimental encephalomyelitis in Lewis rats.

Probiotics beneficial effects on the host are associated with regulation of the intestinal microbial homeostasis and with modulation of inflammatory immune responses in the gut and in periphery. In this study, we investigated the clinical efficacy of two lactobacillus and two bifidobacterium probiotic strains in experimental autoimmune myasthenia gravis (EAMG) and experimental autoimmune encephalomyelitis (EAE) models, induced in Lewis rats. Treatment with probiotics led to less severe disease manifestation in both models; ex vivo analyses showed preservation of neuromuscular junction in EAMG and myelin content in EAE spinal cord. Immunoregulatory transcripts were found differentially expressed in gut associated lymphoid tissue and in peripheral immunocompetent organs. Feeding EAMG animals with probiotics resulted in increased levels of Transforming Growth Factor-ß (TGFß) in serum, and increased percentages of regulatory T cells (Treg) in peripheral blood leukocyte. Exposure of immature dendritic cells to probiotics induced their maturation toward an immunomodulatory phenotype, and secretion of TGFß. Our data showed that bifidobacteria and lactobacilli treatment effectively modulates disease symptoms in EAMG and EAE models, and support further investigations to evaluate their use in autoimmune diseases.