Normal Gut Flora
Everyone has a personal microbial fingerprint. Our blend of bacterial flora is constant over time. Bacterial cells make up most of the material in the colon and 60% of the mass of faeces. Somewhere between 300 and 1000 different species live in the gut, with most estimates at about 500. However, it is probable that 99% of the bacteria come from about 30 or 40 species.
One group of gram-positive, non-sporing bacteria that carry out a lactic acid fermentation of sugars. So called, Lactic Acid Bacteria [LAB], the group includes species of Lactobacillus, Leuconostoc, Pediococcus and Streptococcus .They are vitally important group interacting directly through areas in the gut called Pyers patches to produce components of our immune system
We host other would be pathogenic bacteria, the numbers of which are controlled by healthy amounts of none pathogenic commensal flora. These commensal organisms do not of course present to the immune system as a pathogenic foreign body [antigen] the amazing thing is although they avoid a full blown immune response they do interact through pyers patches to produce lymphocyte's including very special cross reactive antibodies. All commensal flora, friendly and would be pathogens are recognised as self, a consideration of which reflects when working out a treatment.
The picture shows B. fragilis expressing polysaccharide A (green), polysaccharide H (red) or both (yellow).
The commensal microorganisms in the human gut are important to our well-being. Their metabolic capacity has been compared to that of the liver—much of it aiding digestion. The bugs themselves gain a cosy niche, if they can avoid clearance by the host. How they avoid immunosurveillance is unclear, but a study of surface variability reveals that the colonic organism Bacteroides fragilis presents a moving target, modulating surface antigenicity by producing a range of distinct capsular polysaccharides.
Image source: Nature.com
The incidences of autism itself like that of other conditions, learning disabilities, attention deficit hyperactivity disorder (ADHD), asthma, diabetes, arthritis, chronic fatigue syndrome, inflammatory bowel disease and other autoimmune and neurological disorders, has risen dramatically in the U.S. and other technologically advanced countries.
Prof Mark Woolhouse, Chair of Infectious Disease Epidemiology at Edinburgh University says humans risk being overrun by diseases from the animal world, according to researchers who have documented 38 illnesses that have made that jump over the past 25 years.
Each year for the last 25 years, one or two new pathogens and multiple variations of existing threats have infected humans for the first time. Without speculating about earlier infection rates, Woolhouse told reporters it appears impossible the human species could endured such a rapid pace of new infections over thousands of years "Humans have always been attacked by novel pathogens. This process has been going on for millennia. But it does seem to be happening very fast in these modern times,
Prof Woolhouse argues that both many of those diseases and other afflictions will not persist in humans or that there is something peculiar today allowing so many of them to take root in humans.
Autoimmune disorders in the parents of autistic children are much more frequent than in parents of non-autistic children. Many thousands display symptoms of a yeast infection. The western world is also experiencing an explosive growth of Lyme disease and there is a correlation.
THE BENEFITS OF THE NORMAL FLORA
The nature of the interactions between an animal host and its normal flora has been inferred from the study of germ-free animals (animals which lack any bacterial flora) compared to conventional animals (animals which have a typical normal flora). Following are the primary beneficial effects of the normal flora that are derived from these studies.
1. The normal flora synthesize and excrete vitamins in excess of their own needs, which can be absorbed as nutrients by the host. For example, enteric bacteria secrete Vitamin K and Vitamin B12, and lactic acid bacteria produce certain B-vitamins. Germ-free animals may be deficient in Vitamin K to the extent that it is necessary to supplement their diets.
2. The normal flora prevent colonization by pathogens by competing for attachment sites or for essential nutrients. This is thought to be their most important beneficial effect, which has been demonstrated in the oral cavity, the intestine, the skin, and the vaginal epithelium. In some experiments, 10 Salmonella bacteria can infect germ-free animals, while the infectious dose for conventional animals is near 10,000,000 cells.
3. The normal flora may antagonize [block] other bacteria through the production of substances, which inhibit or kill none-indigenous species. The intestinal bacteria produce a variety of substances ranging from relatively none-specific fatty acids and peroxides to highly specific bacteriocins, which inhibit or kill other bacteria.
4. The normal flora stimulate the development of certain tissues, i.e., the caecum and certain lymphatic tissues (Peyer's patches) in the GI tract. The caecum of germ-free animals is enlarged, thin-walled, and fluid-filled, compared to that organ in conventional animals. Also, based on the ability to undergo immunologic stimulation, the intestinal lymphatic tissues of germ-free animals are poorly developed compared to conventional animals.
5. The normal flora stimulate the production of cross-reactive antibodies. Since the normal flora behaves as [none-pathogenic] antigens in an animal, they induce an immunologic response, in particular, an antibody-mediated immune (AMI) response. Low levels of antibodies produced against components of the normal flora are known to cross react with certain related pathogens, and thereby prevent infection or invasion. Antibodies produced against antigenic components of the normal flora are sometimes referred to as "natural" antibodies, and such antibodies are lacking in germ-free animals.
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