The Profound Link Between the Equine Gut and Immunity From Eleanor Kellon, VMD. We typically think of the intestinal tract as a digestive organ, but it has a very important role in the immune system as well. The immune system of the intestinal tract is called GALT – gut associated lymphoid tissue. Throughout the intestinal tract there are immune system cells, macrophages and lymphocytes, under the intestinal lining cells. Structures called Peyers patches are very similar to lymph nodes and are located in the small intestine. Specialized immune cells also line the liver. Microfold cells, or M cells, are located over collections of lymphoid tissue along the intestinal tract. The M cells reach out to engulf bacteria and other material from the intestinal tract then pull it inside and present it to immune system cells. This material is processed through T and B lymphocytes, eventually resulting in the production of IgA antibodies, which remain in the local tissues to protect them. However, it doesnt stop there. The lymphocytes above that will eventually produce local IgA antibody are released into the bloodstream before they come back to home in the intestinal lining again. In the process, they can share this information with the entire bodys immune system so that the rest of the body can produce circulating antibodies (IgG, IgM) to the same organisms the local IgA targets. A good example of how GALT interacts with the rest of the body is oral vaccines. Several human oral vaccines have been developed, including against polio and malaria. Oral rabies vaccines in bait have been used to successfully battle rabies in wild animals. The production of antibodies is only one isolated process in the immune system activity in the gut. Antibodies and cells that target other cells infected with organisms are the effects of the sophisticated arm of the immune system. There is a second arm to the immune system, called the innate immune system. It does not target specific organisms, just has a knee jerk reaction to anything in the blood or tissue fluids it perceives as foreign or harmful, with an inflammatory response. Compare that to the sophisticated arm which targets specific organisms or toxins via antibodies, one type of organism at a time. Its highly specific and doesnt trigger the same large inflammatory reaction. Inflammation and free radical stress are signs that an innate immune response has been triggered. White cells engulf invading organisms and also release cytokines. Cytokines direct cellular activity and cause inflammation. This is an important part of immune defenses but left unchecked it can damage the tissues. Research has found that interactions between the immune system and the bacteria colonizing it can have profound effects. Probiotics are defined as bacterial strains capable of colonizing and surviving in the gut which have a beneficial effect on their host by suppressing the growth of harmful bacteria and interacting with the immune system. Documented effects of probiotics to date include: • control cytokines and direct cellular activity • encourage production of protective mucus by the intestinal cells • reduce inflammation • increase production of IgA while decreasing the risk of allergy Live yeast cultures of Saccharomyces cerevisiae improve fiber digestibility and buffer acid pH but do not have other proven probiotic activity. A 2005 study documented that treatment with Saccharomyces boulardii can decrease the severity and duration of symptoms in horses with enterocolitis, an infection of the intestinal tract. Prebiotics support the growth of probiotic strains of bacteria by feeding them or maintaining an environment in the gut that is favorable for proliferation of probiotic strains. Some also have direct immune system effects. Arabinogalactan, usually isolated from the bark of the Larch tree, has well documented prebiotic effects on probiotic organisms. It also has a stimulatory effect on GALT. Short chain fructooligosaccharides (aka fructans), scFOS, can protect against the gut organism disruptions caused by a sudden increase in grain in the equine diet. L-glutamine is an amino acid, a building block of the antioxidant compound glutathione. Many studies have documented that supplementation with L-glutathione has an antiinflammatory effect in the intestinal tract. Absorbed L-glutamine can also be used to produce glutathione in the liver and other tissues. L-glutamine levels can also be boosted by supplementation with bioactive whey, which is a highly concentrated protein extract of raw milk. In addition, bioactive whey supports normal immune system function, quiets inflammation and autoimmune reactions. In summary, the intestinal tract is a major player in the immune system. It has been estimated that 70% of the immune systems cells originate there. Immune activity in the gut has a bodywide effect. One of the best ways to boost and balance the immune system is through the oral administration of probiotics, prebiotics and other substances documented to support and balance immune function.
Posted on: Fri, 14 Nov 2014 14:19:11 +0000
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