Immunomodulatory Effects of Probiotic Bacteria in Healthy Adults
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View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Helsingin yliopiston digitaalinen arkisto Immunomodulatory Eff ects of Probiotic Bacteria In Healthy Adults Riina Kekkonen Institute of Biomedicine, Pharmacology University of Helsinki Valio Research and Development Helsinki, Finland National Public Health Institute Department of Viral Diseases and Immunology Helsinki, Finland Academic Dissertation To be presented by kind permission of the Medical Faculty of the University of Helsinki for public examination in Lecture Hall 2, Biomedicum Helsinki, Haartmaninkatu 8, on June 6th, 2008, at 12 noon. Helsinki 2008 Supervisors Docent Riitta Korpela, PhD Institute of Biomedicine, Pharmacology University of Helsinki Helsinki, Finland Professor Ilkka Julkunen, MD, PhD Department of Viral Diseases and Immunology National Public Health Institute Helsinki, Finland Reviewers Docent Hannu Kankaanranta, MD, PhD Department of Respiratory Medicine Seinäjoki Central Hospital Seinäjoki, Finland Professor Atte von Wright, PhD Department of Biosciences University of Kuopio Kuopio, Finland Opponent Professor Seppo Salminen, PhD Functional Foods Forum University of Turku Turku, Finland Visual image and layout: Vanto Design Oy /Jaakko Vanto Colour illustrations: Sole Lätti ISBN 978-952-92-3853-8 (paperback) ISBN 978-952-10-4699-5 (PDF) http://ethesis.helsinki.fi Helsinki University Print Helsinki 2008 Table Of Contents Main abbreviations .....................................................................................8 List of original publications.....................................................................9 Abstract .........................................................................................................11 1. Introduction ................................................................................................13 2. Review of the literature ............................................................................15 2.1 Basis for host-probiotic immunomodulatory cross-talk ...............................15 2.1.1 Introduction to the immune system ........................................................................15 2.1.2 Non-immune defence mechanisms .........................................................................15 2.1.3 Intestinal epithelium and recognition of microorganisms ..............................16 2.1.4 Communication within the immune system ........................................................17 2.1.5 Mucosal immunity ........................................................................................................23 2.1.6 Innate immune response ............................................................................................23 2.1.7 Adaptive immune response ........................................................................................24 2.1.8 Importance of regulated immune and infl ammatory responses .....................24 2.1.9 Factors aff ecting the immune system ......................................................................25 2.2 Immunomodulatory effects of probiotics ..............................................................27 2.2.1 Overview of probiotics .................................................................................................27 2.2.2 Possible mechanisms for host-probiotic immunomodulatory cross-talk ... 28 2.2.3 Immunomodulatory properties in human primary cell cultures ...................32 2.2.4 Immunomodulatory properties in healthy adults ...............................................36 2.2.4.1 Assessment of the immunomodulatory eff ects in probiotic interventions .......................................................................................36 2.2.4.2 Immunomodulatory eff ects of probiotics .....................................................39 2.2.4.3 Eff ect of probiotics on clinical outcome .......................................................49 2.2.5 Safety of probiotics ........................................................................................................54 3. Aims of the study .......................................................................................55 4. Materials and methods .............................................................................57 4.1 Bacterial strains ............................................................................................................... 57 4.2 Primary cell culture using peripheral blood mononuclear cells ............57 4.2.1 In vitro ............................................................................................................................... 57 4.2.2 Ex vivo ...............................................................................................................................59 4.3 Subjects and study designs ............................................................................................60 4.4 Immunological and biochemical measurements .................................................63 4.5 Global serum lipidomics profi ling ...........................................................................65 4.6 Questionnaires .................................................................................................................... 65 4.7 Compliance to the probiotic interventions .........................................................66 4.8 Statistical analysis ............................................................................................................ 67 4.9 Ethics ........................................................................................................................................ 68 5. Results ..............................................................................................................71 5.1 Cytokine responses in peripheral blood mononuclear cells in vitro...... 71 5.2 Immunomodulatory effects of probiotics in healthy adults in clinical studies ............................................................................................................. 72 5.2.1 Serum CRP ......................................................................................................................72 5.2.2 Serum cytokines ............................................................................................................73 5.2.3 Cytokine responses in peripheral blood mononuclear cells ex vivo ..............73 5.2.4 Ratio between IL-10 and IL-12 produced by peripheral blood mononuclear cells ex vivo ...........................................................................................75 5.2.5 Correlation between serum cytokine levels and cytokines produced by peripheral blood mononuclear cells ex vivo ..................................76 5.2.6 Leukocytes, lymphocyte subtypes and immunoglobulins ................................77 5.3 Global serum lipidomics profi les ..............................................................................78 5.4 Clinical outcome ............................................................................................................... 80 5.5 Compliance and recovery of probiotic strains in faeces ...............................81 6. Discussion ................................................................................................... 83 6.1 Methodological aspects ................................................................................................. 83 6.1.1 Selection of strains ........................................................................................................83 6.1.2 Primary cell culture model using human peripheral blood mononuclear cells .............................................................................................84 6.1.3 Subjects .............................................................................................................................85 6.1.4 Designs of intervention studies.................................................................................85 6.1.5 Immunological and biochemical measurements ................................................86 6.1.6 Questionnaires ...............................................................................................................87 6.2 Main fi ndings ........................................................................................................................88 6.2.1 Production of cytokines in peripheral blood mononuclear cells in vitro ..... 88 6.2.2 Immunomodulatory eff ects of probiotics in healthy adults ............................90 6.2.3 Global serum lipidomics profi ling ..........................................................................92 6.2.4 Clinical outcome ........................................................................................................... 92 6.2.5 Relationship between in vitro, ex vivo and in vivo results ................................... 94 6.3 Clinical relevance and future aspects ....................................................................95 7. Summary and conclusions ..................................................................... 97 Acknowledgements .........................................................................................99 References .........................................................................................................103 Original publications ...................................................................................121 Main Abbreviations B. Bifi dobacterium Bb12 Bifi dobacterium animalis ssp.