Divergent Patterns of Colonization and Immune Response Elicited from Two IntestinalLactobacillusStrains That Display Similar Properties In Vitro

Abstract

Lactobacilli derived from the endogenous flora of normal donors are being increasingly used as probiotics in functional foods and as vaccine carriers. However, a variety of studies done with distinct strains of lactobacilli has suggested heterogeneous and strain-specific effects. To dissect this heterogeneity at the immunological level, we selected two strains of lactobacilli that displayed similar properties in vitro and studied their impact on mucosal and systemic B-cell responses in monoxenic mice. Germfree mice were colonized with Lactobacillus johnsonii (NCC 533) or Lactobacillus paracasei (NCC 2461). Bacterial loads were monitored for 30 days in intestinal tissues, and mucosal and systemic B-cell responses were measured. Although both Lactobacillus strains displayed similar growth, survival, and adherence properties in vitro, they colonized the intestinal lumen and translocated into mucosal lymphoid organs at different densities. L. johnsonii colonized the intestine very efficiently at high levels, whereas the number of L. paracasei decreased rapidly and it colonized at low levels. We determined whether this difference in colonization correlated with an induction of different types of immune responses. We observed that colonization with either strain induced similar germinal center formation and immunoglobulin A-bearing lymphocytes in the mucosa, suggesting that both strains were able to activate mucosal B-cell responses. However, clear differences in patterns of immunoglobulins were observed between the two strains in the mucosa and in the periphery. Therefore, despite similar in vitro probiotic properties, distinct Lactobacillus strains may colonize the gut differently and generate divergent immune responses.The gut-associated lymphoid tissues are highly compartmentalized. The Peyer's patches are organized lymphoid tissues in the wall of the small intestine that contain B-lymphoid follicles and interfollicular populations of T cells. The lamina propria consists of large numbers of lymphoid and myeloid cells, particularly immunoglobulin A-positive (IgA ϩ ) plasmablasts, scattered under the gut epithelium. Intraepithelial lymphocytes composed mostly of CD8 ϩ T-cell subsets are interspersed within the enterocyte monolayer. It is becoming clear that the quantity and quality of the cells that populate these compartments depend on continuous stimulation provided by the endogenous intestinal microflora (9).Early studies by Schaedler et al. (36,37) contributed to the identification of members of the indigenous gut flora of mice and described the colonization of germfree mice with monocultures of these bacteria, mainly lactobacilli, enterococci, coliforms, and clostridia. Colonization of germfree mice with different mixtures of such commensal bacteria led to the rapid appearance of IgA ϩ plasma cells in the lamina propria (13, 28). Since then, germfree mice have become the model of choice to study the impact of the microflora on gut-associated lymphoid tissue development (7, 9).It was reported by several groups (...

The Effect of Synbiotic Supplementation on Body Composition and Lipid Profile in Patients with NAFLD: A Randomized, Double Blind, Placebo-Controlled Clinical Trial Study

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Probiotics and immunity

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The genome sequence of the probiotic intestinal bacterium Lactobacillus johnsonii NCC 533

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