In this second in a series of posts explaining the concepts that I think are central, but misunderstood, about health, I am focusing on how diet and gut flora impact the immune system and cause autoimmunity and allergies. This cause also suggests a simple cure.
Gut Flora to Tregs to Suppression of Autoimmunity
It is important to understand at the outset that autoimmunity and allergies are caused by a damaged immune system, and repairing the damage cures the diseases. Damage to the immune system typically represents a break in the continual development of immune cells in the lining of the intestines. Immune cell development in the gut is dependent on bacteria, the gut flora. Damage to the gut flora, e.g. by antibiotics, processed foods that lack flora feeding fiber or extreme diets, disrupts development of immune cells. Typically, loss of the immune cells that keep the aggressiveness of the immune system in check, regulatory T cells or Tregs, results in autoimmunity. Fix the gut flora and autoimmunity recedes.
Health Requires Suppression of the Aggressive Immune System
For simplicity, I am focusing on the T cells of the immune system that develop in the intestines and either kill other human cells that are dangerous, e.g. virus-infected or cancer cells, or provide protection by regulating the aggression, Tregs. Normal functioning of the immune cells permits elimination of damaged or dangerous human cells, while at the same time avoiding rampages of lethally armed T killers. Examples of untamed T killers in action are degenerative autoimmune diseases, such as arthritis, asthma, prostatitis, celiac, Hashimoto’s thyroiditis, type I diabetes, inflammatory bowel diseases and atherosclerosis.
Milk Births Baby Immune System
It should not be surprising that the focus of immune system development is the gut. We start as babies with explicit links between nourishment and immunological protection. Milk connects the immune systems of mother to baby. Immune cells from the mother are transferred in milk and colonize the respiratory and digestive system of the baby — the mother’s immune system coats and buffers the baby’s exposure to the world. Milk hormones close the baby’s gut and milk bacteria are the first probiotics that exploit the milk prebiotics (bifidus factor, human milk oligosaccharides) to produce a gut flora. [Also note that most commercial probiotics are adapted to grow on cow’s milk and hence these dairy probiotics do not survive in adults.] The lymphatic system of the breast terminates at the nipple and samples antigens/pathogens from the baby’s mouth, resulting in baby-specific secretory antibodies that return in the milk. Milk supports a starter set of gut flora, essentially dairy probiotics, that stimulates development of the baby immune system, but inhibits adult gut flora that would digest the protective components of milk. Formula, on the other hand, is inflammatory to the baby gut, because it supports adult gut flora before the immune system is ready. Inflammation and stimulation of innate immunity is sufficient, if supported with high levels of sanitation, to permit survival of babies fed formula. Milk of any type is incompatible with adult gut flora, so breast milk will attack adult gut flora and adult gut flora will digest and inactivate the otherwise beneficial components of the milk.
Aggressive and Suppressive Cells of Immune System Develop in Intestines
Gut bacteria are required for the development of immune T cells in the lining of the intestines. Mice grown without gut flora do not have functional immune systems. In humans, extensive antibiotic treatment produces defective immune systems that are either overly aggressive, i.e. autoimmune, or susceptible to infection and cancer. They can’t be both. Aggressive T killers are stimulated to develop by filamentous bacteria and Tregs develop in response to members of the Clostridium family. In a healthy body, there is a balance between aggression and suppression; there are functional defenses against infection and cancer, while also avoiding autoimmune disease and allergies.
Suppressive Tregs are Deficient in Autoimmunity
Immune cells result from replicative divisions of stem cells. Antibody producing B cells are produced through a million random rearrangements of antibody genes and those B cells producing antibodies against common self proteins are killed (clonal deletion). Similarly, T cells are produced by rearrangements of receptors and those that would recognize self are eliminated. The T cells then migrate to the intestines where they can develop into killer T cells or Tregs, in response to gut flora. The Tregs act to suppress killer T cells that mistakenly recognize healthy self cells. Thus, the initial elimination of self-attacking T cells or for B cells that produce antibodies that bind to normal cells, is not perfect and the Tregs are needed to avoid the mistakes. Tregs are necessary to avoid the immune attack on healthy cells that is the basis of autoimmunity.
Autoimmunity Starts with Inflammation, but Requires Deficient Tregs
Bacterial or viral infections, or physical damage causing inflammation is the first step in autoimmunity. It is the inflammation that initiates the interactions between proteins, autoantigens, of normal cells and cells of the immune system that bind, internalize, fragment and present the antigen fragments/peptides to activate B or T cells with corresponding receptors. The activated B cells make antibodies specific for the antigen and the T cells will kill cells displaying the antigen. It is interesting that most proteins are not autoantigens and are never involved immune reactions. Only proteins with an unusual triplet of basic amino acids, similar to the quartet of basic amino acids used to transport proteins into the cell nucleus, are candidates to be autoantigens or allergens. In fact, since nuclear proteins already have a quartet, i.e. the nuclear localization signal, they are common autoantigens. The last requirement for autoimmunity is a deficiency in Tregs, because if the Tregs are functioning, they will block attack on healthy cells. Treg deficiency usually results from loss of the type of gut bacteria that stimulate Treg production in the lining of the intestines, i.e. species of Clostridium.
Hospitals are Notorious for Clostridium difficile Infections
Fecal transplants are now recommended as a safe and efficacious treatment for C. diff hospital infections. That makes sense, because hospitals are where antibiotics are routinely used and C. diff can only infect people missing their healthy species of Clostridium. Thus, the hospitals wipe out the gut flora with antibiotics and then recolonize them with their own antibiotic resistant C. diff. More antibiotics can’t fix it, but providing healthy gut flora (transplant) can.
Autoimmune Diseases are Treated/Exacerbated with Antibiotics
Both the aggressive and the suppressive immune cells require gut flora, so after initial antibiotic treatment wipes out bacteria required for suppression and results in autoimmunity, the remaining aggressive half of the immune system can be eliminated by blasting the remaining gut flora with more antibiotics. Of course this will leave a highly compromised, incompetent immune system that will ultimately yield more extreme symptoms. This is the typical medical progression for Crohn’s disease, for example. The alternative is just fixing the gut flora to begin with and curing autoimmunity.
Cure Autoimmunity by Feeding Clostridium Resistant Starch
Autoimmune diseases, by their symptoms, show that sufficient gut flora to stimulate the aggressive half of the immune system is still present. What is missing are the Clostridium species that convert soluble fiber, such as resistant starch, into short chain fatty acids, e.g. butyrate. Patients treated with antibiotics usually walk away from the hospital with a suggestion to eat some yogurt to repopulate their missing gut flora. Unfortunately, dairy probiotics don’t survive in the gut and cannot repair the gut flora and immune system. The result, after the gut fails to repair and the immune system crashes, is autoimmunity. There is a more appropriate possibility to avoid or fix autoimmunity. Some people suffering from autoimmunity (and with remnants of their gut flora intact) have simply fed their gut flora on resistant starch and achieved complete recoveries. Others fail to respond, because their gut flora is too severely damaged and necessary bacterial species are gone. Those individuals need to eat the missing species of bacteria and some probiotics (more common in Asia) contain Clostridium species. Consistent with this use of soluble fiber to feed gut bacteria that produce butyrate and stimulate the suppressive immune system are reports of healing by combining potato starch (RS) and probiotics with Clostridium butyricum (Probiotic-3). Repair of the suppressive immune system by repair of gut flora (including fecal transplants) and feeding gut flora with appropriate soluble fiber, may be a general approach to the cure of most autoimmune diseases and allergies.