The genomeceutical effect of probiotics and their potential role in quenching autoimmune diseases and disorders of inflammation

Townsend Letter for Doctors and Patients, May, 2004 by Mark A. Brudnak, Llori M. Valenzuela

Abstract

Probiotics are living microorganisms, which when ingested or locally applied in sufficient numbers, confer one or more specified demonstrated functional or health benefits for the consumer (EFFCA, European Food and Feed Culture Association, 2003). Probiotics are also referred to as the "friendly," "beneficial," or "good" bacteria which when ingested act to maintain a healthy intestinal tract and help fight illness and disease. Genomeceuticals are natural ingredients (in this case, probiotics), which can beneficially affect gene expression. Our group has spent decades studying the various health aspects of probiotics. We realized that there is probably a direct correlation between the intestinal flora and health of the human organism with regards to potential autoimmune diseases and disorders of inflammation. In this paper, we will discuss the immunomodulatory effects of probiotics, specifically their role in down-regulating certain immune responses. We propose the use of probiotics to quench the immune system under certain conditions, as well as a mechanism by which such beneficial modulation may be achieved.

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Introduction

More than 400 species of bacteria naturally reside in the digestive tract. The bacteria function to break down food, freeing nutrients for absorption. Many vitamins and essential amino acids are only absorbed after being broken down by gut microorganisms. The proper balance of good bacteria prevents detrimental organisms from invading the gut and leaving the gastrointestinal (GI) tract susceptible to ailments. (1) The consumption of probiotics in cultured milk products, such as yogurt, has been a daily part of the Japanese and European healthy diet for many decades.

As far back as recorded history, communities have embraced certain foods for their believed healing powers beyond basic nourishment. For instance, fermented dairy products have been used for centuries to prevent and/or treat common intestinal problems. Two different probiotics, Lactobacillus and Bifidobacteria, are present in high numbers in fermented dairy products, including yogurt and keifer, and are generally associated with the most probiotic activity. For generations, people have consumed these foods to improve the balance of beneficial microorganisms in the gut and enhance their immune function.

How They Work

The exact mechanism by which probiotics function in the gastrointestinal (GI) tract is not fully understood. However, they are believed to confer health benefits by at least one of the following mechanisms: competitive exclusion of enteric pathogens, neutralization of dietary carcinogens, production of antimicrobial metabolites, and modulation of mucosal immune responses.

The proper balance between good and bad bacteria largely determines the health of the gut and as we are learning, the organism as a whole. Probiotics may help prevent an imbalance in which too many harmful bacteria reside in the digestive tract. A growing body of evidence has emerged confirming the positive effect and potential of probiotics in humans. Recent research has implicated probiotics in the treatment of other diseases, including atopic eczema, autism, cancer, and food allergies. (2) However, to date, the vast majority of studies have focused on the defense and integrity of the intestinal flora and the immune system.

Probiotics may (not necessary for all benefits) take up residence in the body and neutralize the effects of offending bacteria. They colonize the exterior surface of cells in the GI tract and prevent potentially detrimental pathogenic organisms from proliferation. Probiotics also produce components shown to hinder the growth of certain types of harmful bacteria, as well as lowering the risk for altered metabolic activity.

Strong scientific evidence supports the effects of probiotics on the immune system, providing irrefutable evidence that certain probiotic strains play a role in modulating both nonspecific and specific host immune responses. Nonspecific, or innate, immune responses are a host's first line of defense. Natural killer cells and phagocytes, residing in the peripheral blood and tissues, are the major cellular effectors of nonspecific immunity. Natural killer cells effectively fight off viruses, whereas phagocytic cells protect against microbial infections. Both produce a variety of compounds that can destroy both invasive materials as well as normal tissues.

Specific immune responses can be separated into two categories: humoral immunity, and cell-mediated immunity. In the humoral immune response B lymphocytes synthesize specific immunoglobulin molecules, or antibodies, that are excreted from the cell and bind to the invading substance. In the cellular immune response, T lymphocytes, bearing immunoglobulin-like molecules on their surfaces, recognize and kill foreign or aberrant cells. T cells can be divided into 2 subtypes based on their cytokine profile, Th1 and Th2. Th1 cells are essential to cell-mediated immunity and produce IL-2, IFN-[gamma] and tumor necrosis factor [alpha] (TNF-[alpha]). The main products of Th2 are IL-4, IL-5, and IL-10 and are associated with humoral immunity and allergic responses.