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Lactobacillus casei Cell‐Surface Components and Their Impact on Immunomodulation and Cecal Microbiata Composition
Author(s) -
Aktas Busra,
De Wolfe Travis J.,
Safdar Nasia,
Darien Benjamin J.,
Steele James L.
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.892.2
Subject(s) - lactobacillus casei , probiotic , biology , immune system , microbiology and biotechnology , cytokine , innate immune system , in silico , lipoteichoic acid , gut flora , bacteria , food science , immunology , fermentation , gene , biochemistry , genetics , staphylococcus aureus
Lactobacillus casei are commonly utilized as a probiotic in a wide‐range of fermented and unfermented dairy products. Previously it has been shown that L. casei have extensive strain‐to‐strain genetic variation and that significant strain‐to‐strain differences are present in their ability to alter the gut microbiota and modulate the host innate immune system. The objective of this study is to evaluate L. casei for potential mechanisms resulting in the observed probiotic function. We utilized comparative in silico analysis to investigate genes putatively encoding surface components, including: proteins exposed to the surface; pili; wall teichoic acids (WTA); and lipoteichoic acids (LTA). We also evaluated in vitro the ability of six L. casei strains to modulate cytokine production (IL‐10 and IL12) by intestinal epithelial cells (IEC‐6). Additionally, we investigated the contribution of cell surface components and small molecules produced by L. casei to their probiotic function by examining the effect of live, UV‐killed, and supernatants from L. casei strains on cytokine production by IEC‐6. To evaluate the ability of UV‐killed L. casei to alter the gut microbiota and modify the immune system in vivo , we fed mice L. casei 32G at dose of 10 8 CFU/day/mouse for seven days and sacrificed 3.5h after the last administration. The cecal content and the ileum tissue were collected for microbiota analysis and immune profiling, respectively. The in silico results demonstrated that there is an extensive genetic diversity within L. casei cell surface components. The in vitro cytokine assay revealed that the strains modulate cytokine expression in a strain specific manner. The cell surface component of all the strains examined reduced the IL‐10 expression while small molecules were determined to modulate IL‐12 expression in some strains, indicating that both cell surface components and small molecules participate in immunomodulation. The in vivo results demonstrated that only live 32G significantly altered the overall microbiota. The effect of live and UV‐killed 32G on the expression of genes involved in innate immune system was gene specific. In conclusion, significant variation occurs between L. casei strains in the mechanism by which they signal with the host innate immune system and hence their mechanisms of probiotic action. Support or Funding Information This work was funded by the DuPont Inc (Grant no. PRJ19MQ) and by the WARF (Grant no. PRJ66JZ)