Celiac, Gluten and Trypsin Inhibitor

---the other 200 posts---   

Wheat

Summary

Forget the gluten.  Celiac is caused by trypsin inhibitors (ATI) that were increased in wheat fifty years ago to combat pests.  Immune response to ATI spreads to include gluten and transglutaminase that perpetuates the disease.  Celiac is an unexpected consequence of traditional plant breeding that could be fixed with GMO approaches.

Plants Protect Themselves with Antibiotics, Pesticides and Trypsin Inhibitors.

Plants respond to pathogens and pests by making themselves toxic.  Thus, plants produce natural antibiotics, phytoalexins, a.k.a. phytochemicals, polyphenolics or antioxidants, to kill bacteria and fungi.  They also produce chemical pesticides and proteins, e.g. trypsin inhibitor, that block the digestion and utilization of plant proteins by insects.  One of these trypsin inhibitors makes ground soybeans inedible until it is removed in water rinses during the production of tofu.  Another of these trypsin inhibitors, in wheat, is the cause of celiac.

Plants Target the Nerves, Immune Cells and Intestines

Plants have evolved chemicals and proteins that attack and punish plant-eating animals.  A single molecule of caster bean toxin protein, for example, can kill a human cell.  Plants produce some of the most toxic molecules on earth.  The nervous system of insects and other herbivores is typically targeted by plants.  Many recreational drugs, e.g. opioids, THC, nicotine, caffeine, etc., for example, are made by plants in self defense.  Human nerves respond to these natural pesticides and the bitter taste and the vomit reflex help us to detect and avoid toxic phytochemicals.  Gluten proteins contain polyglutamine stretches of amino acids that resist digestion and bind to intestinal cells.  Seed lectins bind to the glycoproteins on the surface of the intestines and inhibit digestion.  Wheat seeds also contain an inhibitor of starch and protein digestion, the amylase/trypsin inhibitor, ATI.  ATI binds to the receptors on immune cells that trigger general inflammatory responses to pathogens, e.g. TLR4.  It is the ATI in wheat that starts an immune response to gluten and celiac.

Wheat trypsin inhibitor causes celiac and autoimmunity

ATI Increased to Make Wheat Resistant to Pests

More than fifty years ago, plant breeders began to screen wheat varieties for resistance to pests.  Breeding ultimately resulted in enhanced pest resistance that resulted from increased production of ATI in wheat kernels.  Modern wheat flour contains modest changes in gluten and other components over the last century with the singular exception of ATI, which has increased about 50 fold.  It is also interesting that ATI is a major wheat allergen.  This suggests that celiac starts as an allergy to ATI present in wheat flour.

Celiac Results from Superfine Milling of High-ATI Wheat

Wheat has been milled more and more finely to improve the shelf-life of bread flour.  The inedible bran and the germ are first removed from the wheat kernels and then the endosperm is ground so finely that the starch granules are broken.  Even "whole wheat flour" is ground in the same way and the bran and germ are simply added back to make it “whole.”  The important point here is that superfine milling results in starch that is readily digested by amylase in the small intestines, instead of acting as soluble fiber to feed gut flora.  The result of eating bread from superfine flour is that gut flora are starved for soluble fiber and the immune system is depleted of Tregs that would otherwise suppress allergy and autoimmunity.  Superfine milling of high-ATI wheat presents ATI to an immune system that is primed for allergy.

ATI is a Good Immunogen

Allergy development requires 1) inflammation, 2) an appropriate immunogen and 3) lack of Tregs (immune system cells that develop in the lining of the intestines and block allergies and autoimmunity.)  The modern milling of wheat flour eliminates a major source of soluble fiber, starves gut flora and reduces Tregs, but allergy development still requires inflammation and an appropriate immunogen.  An immunogen is a protein that will interact with cells of the immune system to produce antibodies and activate aggressive attacks.  I have found that all proteins of food or the environment, i.e. allergens, or of the body, i.e. autoantigens, that act as immunogens to initiate allergies or autoimmunity have the same sequence of three amino acids, a "basic triplet."  ATI has a characteristic basic triplet in its protein amino acid sequence and that is why it is a good immunogen to initiate allergies.

Allergy to ATI is Aggrevated by TLR Recognition of ATI

ATI enriched, superfine flour Is a powerful initiator of allergies, because it starves gut flora to block Treg production and is a good immunogen, but the immune system will still ignore ATI in the gut, unless inflammation is also activated.  Unfortunately, ATI actively stimulates inflammation of the intestines by specifically binding to TLR4, which is the receptor that also binds/recognizes the LPS of bacteria.  Thus, ATI is a way for the wheat plant to defend its seeds by triggering excessive Intestinal inflammation.  Inflammation, immunogen and Treg insufficiency is the ATI allergy trifecta.

Wheat ATI Allergy Leads to Celiac

First exposure to ATI and development of an allergy will make subsequent expose to wheat proteins more immunologically intense.  I discussed the response of the intestinal lining to gluten in previous posts.  Wheat gluten proteins are adapted to provide nutrients for growing wheat embryos and to provide defense against pathogens and herbivores.  Gluten proteins contain long stretches of amino acid glutamine, which is poorly digested by gut enzymes.  The glutamine is also converted into glutamate by the gut enzyme, transglutaminase, tTG.  Unfortunately, during the process, the enzyme is covalently connected to the undigested gluten fragments.  The allergic ATI reaction combined with gluten/tTG conjugates, leads to presentation of the gluten/tTG to the immune system and antibody production agains both gluten and tTG.  Subsequent exposure to gluten results in the autoimmune disease of celiac.

Celiac is Self-Perpetuating

The aggressive immune attack on the intestines in response to eating gluten-containing grains, is bad in itself, but it also causes a series of related autoimmune diseases.  Attack on the intestines also disrupts the development of the lining of the intestines, which in turn disrupts the community of bacteria and fungi, gut flora, that are essential for digestion of plant polysaccharides, soluble fiber, and the development of the immune system.  Gut flora dysfunction results in vitamin deficiencies, food intolerances and autoimmunity.  Thus, celiac is self-perpetuating, because it causes inflammation, immunogen presentation and Treg deficiency.

Celiac Causes Numerous Autoimmune Diseases

Celiac is often associated with other autoimmune diseases, because it causes them.  Antibodies to tTG are diagnostic for celiac and the autoimmune attack on the intestines is mediated by anti-tTG antibodies.  But anti-tTG antibodies of celiac don’t just attack the intestines, they attack any other tissues that have tTG, such as the thyroid gland and hair follicles.  Thus, it should not be a surprise that celiacs are at high risk for autoimmune disease, e.g. Hashimoto’s thyroiditis, of the thyroid gland, including both hypothyroid and hyperthyroid diseases, depending on which region of the thyroid is attacked.  Some forms of hair loss, alopecia, are also initiated by autoimmune attack on the tTG in hair follicles.  Persistent exposure of celiacs to gluten will result in a cascade of autoimmune diseases as other body antigens are presented to the immune system and tissues with those antigens are targeted and attacked to produce arthritis, vitiligo, etc.

Pest Resistance, Plant Breeding and GMO Solutions

Genetic modification of plants occurs every time seeds are planted.  Traditional plant breeding by selecting desirable individual plants grown from crosses of selected parents is one form of genetic modification.  Specifically introducing desired genes using recombinant DNA techniques is another, more controlled method.  Traditional plant breeding has systematically destroyed the diversity of crop plants by loss of genes that are not selected, but even the traits, such as pest resistance, that provide benefit, have also brought unintended consequences.  We now have grains with many desirable features of high yield and disease resistance, but they also provide increased risk of celiac, gluten intolerance and associated autoimmune diseases.  Maybe it is time to consider GM techniques as a safer alternative to fix modern wheat and to examine milling approaches to save our gut flora.

Health Diagrams II — Curing Autoimmunity and Allergies

Cure for Celiac and Autoimmunity

Celiac and other autoimmune diseases are perpetuated by the presence of the corresponding autoantigen/allergen, in this case tTG and gluten proteins, and a deficiency of Tregs.  Oddly enough, some pathogens (Helicobacter pylori) and parasites (Helminth worms) stimulate Treg development in the lining of the intestines, in addition to normal gut flora, Clostridium spp.  It may be the relative absence of pathogens and parasites in affluent societies that reduces Tregs and enhances the incidence of allergies and autoimmunity.  Antibiotics and the antibiotic activity of pharmaceuticals in general may also contribute to Treg deficiencies by damage to gut flora.  Clearly, the repair of gut flora and reestablishment of the associated immune system will go a long way toward curing autoimmune diseases such as celiac.  Celiac, however, provides the added complexity that it damages the ability of the intestines to maintain a functional gut flora.  Thus, the cure for celiac would require simultaneous repair of both the gut and its flora, e.g. by a  fecal transplant and supportive diet containing numerous soluble fibers to which the donor flora have been previously adapted, i.e. lacking antigenic triggers.

Antibiotics, Gluten, Hashimoto's Thyroiditis and Baldness

My impression is that Hashimoto's is caused by a combination of an initial immune attack on the thyroid and incompetent regulatory T cells.  In most cases the immune attack on the thyroid is a secondary consequence of celiac/gluten intolerance, in which anti-transglutaminase antibodies attack transglutaminase bound to gluten in the intestines.  Transglutaminase  is an enzyme that is also produced by the thyroid (and hair follicles) and attack by celiac antibodies can enhance or inhibit thyroid hormone production (or baldness.)  Both Hashimoto's and celiac do not occur if the suppressive part of the immune system, i.e. regulatory T cells, is functioning.  

Antibiotics Compromise the Immune System

The major point here is that antibiotics disrupt normal bacterial biofilms that line the intestines and these healthy gut bacteria are required for development of regulatory T cells.  Compromise of Tregs leads to autoimmune diseases, e.g. celiac, Hashimoto’s and baldness, and also allergies.

Antigens/Allergens Have Basic Amino Acid Triplets

The antigens targeted in autoimmune diseases, e.g. tTG, anti-nuclear, TPO, and allergies form an obvious pattern.  All of these antigens and allergens have simple amino acid sequences (rare patches of three basic/positively charged amino acids) that enhance their presentation to the immune system to produce antibodies.  Nuclear proteins, for example, are frequent autoantigens and most of these proteins interact with nucleic acids (negatively charged) and have predictable patches of positively charged amino acids (arginine and lysine).  Other common autoantigens have basic amino acid (arg/lys) patches, because they interact with phospholipids (also negatively charged.)  Proteins with basic patches, e.g. HIV-TAT or heparanase, are also readily transported into cells and nuclei.  Peptides with these sequences are produced by action of stomach enzymes on proteins, e.g. milk lactoferrin, and are antimicrobial.

Allergies / Autoimmune Diseases Are a Predictable Consequence of Antibiotics

Doctors treat with antibiotics, but they fail to repair damage that they cause to gut flora.  The gut flora of most patients treated with antibiotics, especially those who are most fastidiously hygienic, never fully recover.  Constipation is a common symptom of severe dysbiosis and related immunoincompetence.  Probiotics are gut flora bandaids and do not survive as components of gut flora.

Gut bacteria are also needed for development of the aggressive part of the immune system.  Thus, autoimmune diseases can be treated with even more intense use of antibiotics, that will eliminate the rest of the immune system.  Since all vitamins are produced by gut flora as quorum sensing signals, antibiotics can also produce the exotic symptoms of vitamin deficiencies.

Antibiotics are essential to many therapeutic approaches, e.g. surgical procedures or therapy for chronic Lyme disease, but they must be used responsibly and treated patients must be subsequently tested to ensure a repaired gut flora and a functional immune system have been reestablished after antibiotics.  Long term antibiotic use needs special attention, e.g. deliberate Repair of Gut Flora or a fecal transplant.

Thus, I think that it is most likely that ever increasing antibiotic exposure and processed foods, coupled with obsessive hygiene have led to crippled gut flora (as observed in the simplified gut microbiomes of Americans), a net decline in suppressive Tregs and the observed increase of autoimmunity and allergies.  The competence of the immune system may be a major determinant in the course of infection with a pathogen that can produce chronic infections.

Autoimmune Diseases, Bacteria and GALT (Gut Associated Immune System)

Celiac, Oxidative Stress, Peroxiredoxin, Alopecia

Grain/gluten intolerance, celiac is an immunological attack on the small intestines with increased risk for numerous autoimmune diseases.  Hashimoto’s thyroiditis is a common sequela of celiac and the two diseases share the same autoantigen, tissue transglutaminase (tTG).  Thus, the development of celiac and the production of antibodies to the tTG produced in the intestines, results in a subsequent immunological attack on other tissues that produce lots of tTG, e.g. the thyroid.  Gluten intolerance, because of its attack on the intestines and the proximity of a major part of the immune system (GALT), may play a major role as the foundation for autoimmune diseases.

Gluten Intolerance First Step in Autoimmune Diseases

Celiac may also lead to herpatic lesions of the skin, dermatitis herpetiformis and loss of hair, alopecia.  In these cases, the autoantigen is peroxiredoxin, an enzyme that eliminates hydrogen peroxide produced as a result of accumulation of reactive oxygen species, e.g. superoxide, associated with inflammation.  Peroxiredoxin is also implicated as an autoantigen in periodontal disease, suggesting that celiac may also contribute to dental gum inflammation.

Peroxiredoxin 5 Gene Associated with Alopecia Risk

A recent study (see ref. below) of genes associated with alopecia identified genes involved in Treg and Th-17 development, as well as peroxiredoxin 5 as contributors.  As expected, several genes involved in antigen presentation (HLA-DRA, HLA-DQA)  were also identified.  Th-17 lymphocytes are involved in immune attacks on self tissue, i.e. autoimmune diseases, such as alopecia, in which hair follicles are attacked by the immune system.  Tregs control immune attacks on self tissues.  Peroxiredoxin is an autoantigen and is produced in elevated amounts around hair follicles attacked in alopecia.

Basic Amino Acids of Peroxiredoxin as Expected for Autoantigen

I checked the amino acid sequence of human peroxiredoxin 5 and found an alternative (-nrrlkrfsmv-) to the triplet of basic amino acids that I expect for an autoantigen.  In this case there are two adjacent pairs of basic amino acids (blue rr and kr) that I think precipitate immunological presentation of peroxiredoxin.  Peroxiredoxins are produced in response to oxidative stress at sites of  inflammation and the presence of celiac compromises the gut associated immune system (GALT) that provides Tregs to restrict autoimmunity, so celiac sets the stage for peroxiredoxin presentation to the immune system and for subsequent production of anti-peroxiredoxin antibodies, autoimmunity and destruction of hair follicles, alopecia.

Anti-Inflammatory Diet Should Avoid and Treat Autoimmunity

Control of autoimmune diseases mediated by peroxiredoxin should benefit from a reduction in the conditions that spawned the diseases:

• Th-17 elevation -- celiac inflammation stimulated by grain/gluten
• Treg loss -- GALT inactivation due to inflammatory diet and inappropriate gut flora
• Autoantigen (basic amino acid concentration) presentation -- oxidative stress stimulation of peroxiredoxin

Treatment would be supported by dietary changes:

• anti-inflammatory diet to control gut inflammation and minimize celiac symptoms (vitamin D, low carb/high saturated fat, high omega-3 to -6 fatty acid ratio, no grains)
• probiotics and soluble fiber (e.g. pectin, inulin) to re-establish gut flora (cure dysbiotic constipation) and GALT function, and development of Tregs
• supplements to compensate for depletion of vitamin C and glutathione by oxidative stress, e.g. vitamin C and acetylcysteine (NAC)

Th-17 and Tregs in HIV Infections

Th-17 cells are also reduced by HIV infection, producing susceptibility to infection, but this infection should also reduce autoimmune disease.  The reduction in Th-17 also may be a consequence of problems in the GALT.  Therapy for HIV infection should also include diet considerations to increase Th-17 and also Tregs to reduce autoimmune diseases due to unbalanced Th-17.

ref.

Petukhova L, Duvic M, Hordinsky M, Norris D, Price V, Shimomura Y, Kim H, Singh P, Lee A, Chen WV, Meyer KC, Paus R, Jahoda CA, Amos CI, Gregersen PK, Christiano AM.  2010. Genome-wide association study in alopecia areata implicates both innate and adaptive immunity.  Nature. 466(7302):113-7.

Arthritis, Autoimmunity and Arginine Deimidation

Celiac and Antibody Production Against Tissue Transglutaminase as a Model

Arthritis is an autoimmune disease in which the immune system attacks and degrades the connective tissue of joints.  Antibodies against modified amino acids, arginine converted to citrulline, and proteins commonly found in joints, mediate the arthritis disease process.  The development of arthritis mimics the development of gluten intolerance, celiac, in which another enzyme, transglutaminase ( tissue transglutaminase, tTG or TG2) modifies the major gluten protein, gliadin, and antibodies are produced against both modified gliadin and TG2 autoantigen.

Arthritis of Joints Is Like Coeliac of Intestines;  Autoantibodies to Protein Modifying Enzymes

In other articles, I outlined the pathology of gluten intolerance:

• The major protein of wheat gluten, gliadin, contains long stretches of glutamines.
• An intestinal enzyme, TG2, converts the glutamines to glutamates by deamination.
• As TG2 works it binds to gliadin.
• In celiac, the TG2-gliadin complexes are internalized and fragmented to stimulate antibody production against both TG2 and gliadin.
• I think that the internalization and processing for antibody stimulation is dependent on the basic triplet found in TG2.

Arthritis Is Mediated by Autoantibodies to Peptidylarginine Deiminase and Citrullinated Proteins

Parallel to the celiac example, in some forms of arthritis, antibodies are produced against an enzyme that modifies proteins.  In arthritis, the enzyme involved, peptidylarginine deiminase (PAD) removes the terminal nitrogen from arginine (deimination) to produce citrullinated proteins.  Antibodies are produced to both PAD and citrullinated proteins.

PAD Also Has a Triplet of Basic Amino Acids for Internalization

I of course wondered if PAD had the same triplet of basic amino acids, e.g. RRK, that I had found on all other autoantigens and allergens.  Examining the sequence of human PAD in the NCBI sequence databases and comparing to other sequences, I found the basic triplet near the carboxy terminus.  The same or an alternative basic triplet was found in PADs from other mammals.

Autoantigens and Predicted Basic Triplets of Amino Acids Reveal the Cause of Arthritis

Arthritis is an inflammatory disease.  That means that without inflammation, arthritis cannot start and if inflammation is inhibited, arthritis cannot progress.  It is likely that arthritis is the result of chronic inflammation plus a precipitating event, such as joint injury or joint infection.  Alternatively, in a manner similar to Hashimoto’s thyroiditis, in which celiac produces anti-TG2 antibodies that attack the TG2 also produced in the thyroid gland, arthritis may be produced by autoantibodies stimulated in the inflammation of other tissues and spreading to the joints.  Celiac is also a risk factor for arthritis.  Trauma-based inflammation of a joint can also result in migration of Clamydia pneumonia (Cpn)-infected macrophages to the site of inflammation.  Cpn could contribute to joint inflammation and promote immunological presentation of autoantigens and autoantibody production.

reference:
Stenberg P, Roth B, Wollheim FA.  Peptidylarginine deiminases and the pathogenesis of rheumatoid arthritis: a reflection of the involvement of transglutaminase in coeliac disease.  Eur J Intern Med. 2009 Dec;20(8):749-55. Epub 2009 Sep 19.

Cytstic Fibrosis Overproduces Tissue Transglutaminase and Contributes to Celiac

Tissue transglutaminase (tTG or TG2) is produced in excess in some diseases, such as cystic fibrosis, and contributes to inflammation and disease symptoms. tTG also readily moves in and out of cells by virtue of its basic triplet and when in the cytoplasm, tTG is ubiquinated and degraded by proteosomes. I have previously pointed out that internalization and proteosome degradation are also the initial steps in processing of proteins for presentation by the immune system and antibody production, i.e. turning a cellular protein into an autoantigen involved in autoimmune disease.

Here is an image of a computational protein model of tTG I drew with Chimera. I have highlighted the basic triplet to show its exposure to facilitate transport.

Oxidative Stress Alters tTG and Triggers Inflammation

A recent article also links tTG intracellular chemical modifications (SUMOylation), which are linked to oxidative stress, to activation of NFkB and inflammation. Thus, tTG is a major player in controlling cell surface interactions with potentially toxic materials such as polyglutamine-rich gliadin, as well as triggering inflammation in response to oxidation stress.

Cystic Fibrosis Causes Overproduction of tTG

When I read that cystic fibrosis results in an increase in the production of tTG in lungs, I immediately thought of the role of tTG as an autoantigen in celiac disease and the progression of celiac into Hashimoto’s thyroiditis, which has the same autoantigen, tTG. I suspected that the overproduction of tTG and inflammation in cystic fibrosis should increase tTG autoantibody production and tTG-mediated autoimmune diseases of celiac and Hashimoto’s thyroiditis.

Extra tTG Leads to Autoimmune Celiac

A quick PubMed search of CF and celiac, revealed a study of comorbidity between CF and celiac in Norway. Just as expected, the two diseases occur together with a frequency three times higher than predicted by coincidence. CF stimulated tTG overproduction was driving the development of celiac.

references:
Luciani A, Villella VR, Vasaturo A, Giardino I, Raia V, Pettoello-Mantovani M, D'Apolito M, Guido S, Leal T, Quaratino S, Maiuri L. SUMOylation of tissue transglutaminase as link between oxidative stress and inflammation. J Immunol. 2009 Aug 15;183(4):2775-84.

Fluge G, Olesen HV, Gilljam M, Meyer P, Pressler T, Storrösten OT, Karpati F, Hjelte L. Co-morbidity of cystic fibrosis and celiac disease in Scandinavian cystic fibrosis patients. J Cyst Fibros. 2009 May;8(3):198-202.

Celiac Causes Allergies and Autoimmune Diseases

Anti-Tissue Transglutaminase Can Lead to Hashimoto’s Thyroiditis

Celiac, gluten intolerance, causes intestinal inflammation and immunological presentation of the common intestinal protein, tissue transglutaminase (tTG). The result is anti-tTG autoantibodies that stimulate an immune attack on intestines and other tissues.

Heparan-Binding Proteins Involved in Autoimmunity and Allergy

Those familiar with my blog know that I am obsessed with heparin-binding protein domains. The reason that I am focused on these parts of proteins, is because most cells rapidly sweep heparan sulfate polysaccharides across their surfaces from sites of secretion to sites of internalization. During inflammation, proteins with strong heparin-binding domains, consisting of triplets of basic amino acids, e.g. KRK (lysine-arginine-lysine), are internalized along with the heparan sulfate. The result is an aberrant presentation of these internalized proteins to the immune system and production of inappropriate antibodies, e.g. autoantibodies.

Basic Triplets in Hasimoto’s Autoantigens

One of my hobbies is checking for the unusual occurrence of basic triplets in autoantigens and allergens. I have found dozens of examples. The most recent is associated with Hashimoto’s Thyroiditis. I knew that attack on the thyroid was common in celiacs, because the celiac autoantigen tTG (it has a basic triplet) is also present in the thyroid and the celiac autoantibodies to tTG also cause an attack on the thyroid. But the autoantigen for Hashimoto’s Thyroiditis is thyroid peroxidase (TPO).

I was momentarily perplexed, but then examined the TPO amino acid sequence and immediately found a couple of basic triplets (KKR and KRK).

MRALAVLSVTLVMACTEAFFPFISRGKELLWGKPEESRV
SSVLEESKRLVDTAMYATMQRNLKKRGILSPAQLLSFSK
LPEPTSGVIARAAEIMETSIQAMKRKVNLKTQQSQHPTD
ALSEDLLSIIANMSGCLPYMLPPK...


Hashimoto’ Thyroiditis Linked to Celiac

Then, I did a PubMed search for “celiac and Hashimoto’s”. As expected, there is a recent paper (see below) that shows that celiac commonly leads to Hashimoto’s Thyroiditis.

An obvious explanation is that the initial attack on the thyroid by anti-tTG autoantibodies of celiac leads to thyroid inflammation and presentation of TPO, with a second round of autoantibodies produced to TPO resulting in Hashimoto’s Thyroiditis. Celiac may be the initial autoimmune trigger for many other autoimmune diseases and allergies.

Autism has been associated with maternal autoimmunity and placental abnormalities. Guess where tTG is found in high abundance?

reference:
Bardella MT, Elli L, Matteis SD, Floriani I, Torri V, Piodi L. Autoimmune disorders in patients affected by celiac sprue and inflammatory bowel disease. Ann Med. 2009;41(2):139-43.