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Species and Cell Types / Bacterium / Lactobacillus


Does the Gut Microbiota Trigger Hashimoto's Thyroiditis?

Abstract: Hashimoto's thyroiditis is an organ-specific autoimmune disease in which both genetic predisposition and environmental factors serve as the trigger of the disease. A growing body of evidence suggests involvement of viral infection in the development of Hashimoto's thyroiditis. However, not only pathogenic microorganisms but also non-pathogenic commensal microorganisms induce proinflammatory or regulatory immune responses within the host. In accordance, series of studies indicate a critical role of intestinal commensal microbiota in the development of autoimmune diseases including inflammatory bowel diseases, type 1 diabetes, rheumatoid arthritis, and multiple sclerosis. In contrast, the role of the gut and indigenous microorganisms in Hashimoto's thyroiditis has received little attention. Whereas activation of innate pattern recognition receptors such as Toll-like receptors and disturbed intestinal epithelial barrier may contribute to thyroiditis development, only a few studies have addressed a link between the gut and Hashimoto's thyroiditis and provided just indirect and weak evidence for such a link. Despite this unsatisfactory situation, we here focus on the possible interaction between the gut and thyroid autoimmunity. Further studies are clearly needed to test the hypothesis that the gut commensal microflora represents an important environmental factor triggering Hashimoto's thyroiditis. ... Read more

Vaccine Adjuvant Properties of Probiotic Bacteria

Abstract: Vaccine-preventable diseases are still responsible for the deaths of more than 1 million children under the age of 5 years annually, mostly in developing countries. A substantial number of these deaths are due to pneumococcal bacteria and infections with rotavirus. Important issues faced by the WHO, governments, vaccine manufacturers, and international organizations such as UNICEF and the Global Alliance for Vaccines and Immunization (GAVI) are the cost-effective introduction of these life-saving vaccines in resource-poor countries where there is a considerable disease burden, and achieving high rates of completion of vaccination schedules remains elusive. Problems with vaccine coverage and vaccine delivery in these regions are significant, as in some cases large proportions of the target population do not receive adequate vaccination. Consequently, there is a need to develop more effective vaccination strategies that can provide adequate protection with reduced schedules. To date, emphasis has been placed on identifying novel vaccine antigens and adjuvants that induce stronger protective immune responses, as well as developing mucosally-administered vaccines. These approaches would have enormous benefits in allowing safe administration of vaccines in remote areas and may overcome the necessity for multiple doses. In this regard, the use of probiotic bacteria as novel mucosal adjuvants to enhance existing vaccine specific-immune responses offers an exciting new approach. In this review, we discuss the evidence for the role of probiotics in enhancing vaccine responses and provide justification for further investigation into their clinical effects and mechanisms of action. ... Read more

The Role of Microbial Byproducts in Protection Against Immunological Disorders and the Hygiene Hypothesis

Abstract: Over the past three decades the incidence of allergic disorders and autoimmune diseases has risen and this trend is particularly prominent in developed nations. The hygiene hypothesis suggests that as a living environment becomes more sanitized, children are not exposed to microbial and parasitic stimulations that were once commonly acquired since early in life, leading to a lack of immune sensitization tending towards T helper 2 (Th2) dominance. This postulation is sufficient to explain allergic disorders, which mostly result from hyper Th2 responses, but inadequate to explain the increase in Th1 or Th17-based autoimmunity. Recent advances in experimental mouse models revealed that stimulation of Toll-like receptors (TLRs) by pathogen-associated molecular patterns could reduce symptoms of allergic airway disease and prevent the onset of autoimmunity. The underlying mechanism for the protective effects of TLR ligands is currently under intense investigation and there are indications that IL-10-producing B cells, regulatory T cells, and innate immune cells play an important role during this process. The finding that early exposure to microbial byproducts contributes to the modulation of immunological disorders may once again modify our interpretation of the hygiene hypothesis. ... Read more

Gene Therapy for Cancer: Dairy Bacteria as Delivery Vectors

Abstract: The prime obstacle to achieving an effective treatment for cancer is that of eradicating tumors without harming healthy organs and cells of the patient. The concept of utilizing biological agents for delivery of therapeutic genes to patients to kill cancer cells has been under investigation for two decades, which exploits the natural ability of disease causing microbes to invade human cells. Safety-modified versions of pathogenic viruses or bacteria can deposit genes and induce production of anti-cancer agents upon administration to tumors and promising clinical trial successes have been achieved with various types of gene delivery vehicles. Bacteria present an attractive class of gene vectors, possessing a natural ability to grow specifically within tumors following intravenous (IV) injection. Several species such as Clostridium and Salmonella have been examined in clinical trials. However, as foreign, disease-causing bugs, their inherent toxicity has outweighed therapeutic responses in patients, despite efforts to reduce toxicity through genetic modification. A promising alternative exploits non-pathogenic bacterial species that have an existing natural relationship with humans. Our recent study (Cronin et al., 2010) has demonstrated that IV injection or ingestion of a species of probiotic bacterium, Bifidobacterium breve, in high numbers, results in trafficking of the bacteria throughout the body and accumulation specifically within cancerous tissue. ... Read more

Probiotics -- A Viable Therapeutic Alternative for Enteric Infections Especially in the Developing World

Abstract: This review focuses on the most recent advances in the application of probiotics as potential therapeutics for the developing world, from the treatment of chronic and acute enteric infections and their associated diarrheal complexes to the development of designer probiotics for controlling HIV and as novel mucosal vaccine delivery vehicles. ... Read more

Editor's Note -- August 2005

“Between 500 and 1,000 microbial species colonize the mammalian colon to a density of approximately 1012 bacteria per gram of content, comprising in total 100 times more cells than those that make up the host itself,” said Drs. Lanning and Knight in an article published in this issue of the journal. Given the immensity of the bacteria living inside our bodies, it is almost a miracle that they do not cause more trouble than they occasionally do (e.g., diarrhea, enterocolitis, imbalance of intestinal flora, etc.).

On the contrary, the commensal bacterial flora in the gut performs important, unconventional tasks ... Read more

Lactobacilli as Natural Enhancer of Cellular Immune Response

Abstract: Lactobacillus bacteria, which make lactose, line the mucosa of the mouth, intestine and vagina. One important aspect of having them there is to physically occupy the space and nutrients, preventing bad bacteria such as certain strains of E. coli from excessive colonization. Lactobacilli's ubiquitous presence on intestinal mucosa offers a unique opportunity; they could deliver, via molecular engineering, vaccines and drugs to mucosa. ... Read more

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