Where’s the Aspirin?

Aspirin is the traditional anti-inflammatory agent. Many of us grew up with the quintessential doctoring phrase, “Take two aspirin and call me in the morning.” Aspirin stops inflammation in several ways. Like all drugs, it interacts with many different proteins/enzymes. In fact it interacts so intimately with the inflammatory system that it suggests that the process of inflammation may require an aspirin-like molecule to function normally.

Aspirin Binds to Multiple Enzymes of Inflammation

Aspirin is observed to reduce inflammation. That means that ingested aspirin tablet dissolve in the stomach and pass through the intestines into the blood stream and subsequently bath cells of the blood and the endothelium that lines the blood vessels. In order to reach the blood stream, the aspirin must pass through the intestinal cells. That passage requires binding to a protein transport molecule.

Cells responding to an inflammatory signal (NFkB, transcription factor is activated) synthesize enzymes that release unsaturated fatty acids (ARA, EPA, DHA) from membrane phospholipids (PLA2, phospholipase A2), form a cyclic epoxide from the fatty acid (prostaglandin H2 synthase 2, also called cyclooxygenase 2, COX-2).

Aspirin binds to the inhibitor that normally inactivates NFkB and prevents NFkB activation that is required for inflammation. Aspirin also binds to PLA2 and prevents fatty acid release and thereby blocks activation of inflammation. Aspirin also binds to COX-2 and blocks the production of inflammatory prostaglandins from ARA. But that is not all that aspirin does.

Inflammation Resolution Uses Aspirin-COX-2 Interaction

The strange interaction that makes aspirin suspicious is that aspirin doesn’t just interfere with the action of enzymes, it subtly changes their specificity. Thus aspirin chemically transfers its acetyl group (CH3-COOH-) to an amino acid in the active site of COX-2 to produce a new group of anti-inflammatory lipoxins from ARA, EPA and DHA.

This raises the question of whether aspirin is a natural dietary modulator of inflammation. Recall that aspirin was initially obtained from willow (Salix) bark. Unfortunately, the data are conflicting. Initial research indicated that grains (naturally inflammatory) lacked aspirin, but many herbs, spices and leafy vegetables (naturally anti-inflammatory) contained aspirin. Subsequent tests refuted this work. It would be consistent with observations that some dietary components are anti-inflammatory, but candidate acetyl donors have not been identified.

Speculative acetyl candidates may include the menthol relatives, such as menthyl acetate (figure). Peppermint oil, which contains mostly menthol with some menthyl acetate, is more effective in the treatment of inflammatory bowel disease than most pharmaceuticals prescribed to treat the condition. This anti-inflammatory activity may be due in part to the aspirin-like chemical structure and function of the menthyl acetate. Also note that acetic acid/vinegar is sometimes suggested as a cure-all. This activity may be a consequence of its formation of ester linkages with alcohols that have structures similar to menthol.

Large Dose Aspirin as Cancer Treatment

The potent anti-inflammatory effects of aspirin have been compromised, because inflammation is an essential developmental activity. Thus, the integrity of the gut, for example, requires modest production of inflammatory prostaglandins and a pill of aspirin can disrupt gut tissue. Large doses of aspirin cannot be given orally. Intravenous administration of large doses of aspirin, however, is possible and the impact on process that require inflammation is dramatic.

Anecdotal evidence indicates that large dose aspirin is able to disrupt cancers, because proliferation of cancer cells requires NFkB activation and other inflammatory responses. High doses of aspirin also cause other potentially dangerous complications, such as short-circuiting oxidative phosphorylation of mitochondria and increasing nitric oxide free radical production. Still, the impact of high dose aspirin on some diseases is so amazing that it is being actively and carefully pursued.

What’s the Opposite of Inflammation?

I want to commemorate the writing of my 100th article on Blogspot by discussing a new insight into inflammation.

I have been searching the last several years for an anti-inflammatory system to balance inflammation. Now I realize that there is no opposite to inflammation. There is only completion of inflammation to return to the original state. Inflammation is a process that includes resolution or recovery from the defensive, destructive state of immunological activity.

Inflammation is the martialling of resources for battle by offloading lymphocytes from the blood stream, engaging the enemy by triggering the release of toxic secretory vesicles from leukocytes, and cleaning up the carnage by macrophages engulfing cellular fragments. Each step in the inflammatory process induces the next step until there is a return to the origin. Inflammation is not balanced by anti-inflammatory processes.

Inflammation is triggered by molecules characteristic of viruses, bacteria or fungi binding to membrane receptors (TLRs). The result is activation of the inflammatory transcription factor, NFkB (illustrated holding DNA), that turns on the expression of dozens of genes that code for cytokines (IL-1, IL-6, TNF) and enzymes (COX-2) that produce signal compounds. Among the signal compounds are the inflammatory eicosanoids (PGE2) produced from the omega-6 fatty acid arachidonic acid (ARA).

The complex signaling pathways that lead to PGE2 synthesis subsequently initiate transcription of genes that code for the enzymes that make lipoxins (resolvins and protectins) from eicosapentanaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA and DHA are the two omega-3 fatty acid components of fish oil and a shortage of these dietary components blocks the next step, resolution of inflammation.

The lipoxins reduce the permeability of blood vessels, stop the offloading of lymphocytes, reduce responsiveness to inflammatory cytokines, recruit phagocytic macrophages to clean up debris and orchestrate a return to quiescence of the inflammatory system. Without adequate lipoxins, inflammation continues.

An interesting footnote to this discussion is the impact of aspirin on inflammation. Aspirin binds to the enzyme (COX-2) that converts ARA to inflammatory prostaglandins and leukotrienes. Acetylation of COX-2 by aspirin stops inflammatory eicosanoid synthesis and shifts the synthesis to anti-inflammatory lipoxins. Even ARA is used to make anti-inflammatory lipoxins in the presence of aspirin. This shift to anti-inflammatory signaling may occur naturally in the small intestines in response to aspirin-like compounds in vegetables. This would be a transitory response similar to taking aspirin with a meal. More constant use of aspirin would disrupt the normal and necessary actions of the inflammatory signaling to maintain the integrity of the gut.

Excess of dietary omega-6 oils and deficiency in omega-3 fatty acids corrupts inflammatory signaling by eliminating recovery and produces chronic inflammation. Another name for chronic inflammation is obesity/metabolic syndrome. Chronic inflammation is the foundation for the degenerative, autoimmune and cancer diseases that are so prevalent today.

Fortunately a shift to an anti-inflammatory diet and lifestyle provides a simple solution to chronic inflammation.

[Note added: Perhaps the opposite of anti-inflammatory is immunosuppressed, as in high use of omega-3 oils can increase the risk of tuberculosis of influenza.]

There Is More Than Antioxidants

Every time a plant product has an impact on a disease it seems to be attributed to its antioxidant activity. Plant products are active, because they bind to proteins. They bind to lots of different proteins.

Krill oil is a good example. The anti-inflammatory activity of krill oil is due to its omega-3 oil (DHA and EPA) content, but krill oil is more potent than expected. Krill oil also contains a terpene, astaxanthene, that is probably derived from its algae diet. Astaxanthene is labeled as an anti-oxidant, but that is much too easy.

Astaxanthene consists of two flat, hydrophobic paddles, connected by a flexible, hydrophobic chain. Those paddles are important, because of their inability to hydrogen bond with water, i.e. hydrophobicity, and therefore their propensity to get stuck in contact with other hydrophobic surfaces. The list of candidate hydrophobic surfaces includes the obvious smaller aromatic rings (e.g. phenylalanine), indole double rings (e.g. tryptophan), and the less obvious sugars (e.g. galactose), unsaturated lipid/prostaglandins and basic amino acids (lysine and arginine). These are dominant cellular interactions.

The interchangeability of the hydrophobic paddle-binders means that astaxanthene can get its paddles stuck in enzyme or receptor protein active sites that normally bind a wide range of ligands (target small molecules, e.g. enzyme substrates). It is likely, therefore, that astaxanthene has anti-inflammatory activity, because it blocks an inflammatory interaction.

The ubiquity of interactions of terpenoids, based on their general structural properties, also gives these molecules access to cellular cytoplasm. These molecules are too large to diffuse through membranes and if they got half way through, they would be permanently stuck in the membrane. Terpenoids will tend to stick to carrier proteins that have hydrophobic patches or slots. These carriers will transport and internalize terpenoids and other similarly shaped molecules, e.g. steroid hormones.

Metformin, the diabetes drug, is another example of a molecule with a flat, hydrophobic side. It is a stretch to call this an antioxidant, but it is useful for this discussion, since one of my students tested to see it it would stick to a tryptophan in the active site of a classic enzyme, beta-galactosidase. Galactose, in the typical substrate for this enzyme, lactose, will bind to the active site, because of a prominent tryptophan. The shocker is that my student showed that metformin also binds to that same site and competes with lactose. Astaxanthene would also be expected to bind in the same way.

Curcumin is one of the most potent anti-inflammatory compounds and the main ingredient in turmuric, binds to proteins that inhibit the inflammatory transcription factor, NFkB. I would expect astaxanthene to also inhibit NFkB.

Capsaicin is a related molecule that binds to the heat/pain sensor in skin and blocks pain sensation. That is how capsaicin is used as a topical analgesic. Castor oil, ricinoleate, binds to the same sensor and competes with capsaicin and also is an effective pain reliever. Note that ricinoleate is a modified fatty acid that could curl up on the same hydrophobic paddle surface as capsaicin.

The bottom line of this discussion is that if someone tries to convince you that resveratrol, the anti-aging ingredient in wine, is an anti-oxidant, be skeptical. Expect that resveratrol will have numerous interactions with proteins and many of those will not be known.

I Don’t Believe It ...

There are too many myths in biomedical science. I think that our fears are misplaced and if we just address the real threats, e.g. inflammatory vegetable oils, we can enter the New Year with realistic hopes for good health.

Don’t Worry about Genetic Predispositions to Disease

Mendel was wrong in asserting that there is one gene for each phenotype. Modern clearinghouses of genes reveal the relationships between gene sequences and numerous protein functions. In the Human Protein Reference Database (HPRD), for example, each human gene is listed with all of its synonyms. The synonyms frequently reveal that genes lead multiple, unrelated lives and have sundry tangled relationships with dozens of other proteins. So the idea that there is one gene for each physical trait, phenotype, is a misleading simplification.

The good news is that the complexity would only be a problem, if our individual genetic composition was important to our health. In most cases, I think that our individual genetic predispositions to disease would only be important, if we stress our bodies (usually with an inflammatory diet) to the point of failure. With a healthy diet and lifestyle, I don’t think that most genetic predispositions to disease would ever affect health. To be specific, most people should be able to live until 80 with few physical compromises. This is very hopeful.

Don’t Worry about Drug Side-Effects (avoid the need for drugs)

Drugs have many side effects, simply because we don’t know enough about the interactions of small drug molecules with all of the possible protein targets. Take heparin, for example. Heparin is one of the most commonly used drugs to inhibit blood clotting. There is a clotting assay to measure how well heparin blocks clotting and injecting more heparin makes clotting slower. It appears that heparin binds to a protein involved in clotting. Heparin does bind to anti-thrombin, which in turn inhibits thrombin that is needed for clotting. Heparin also binds to several other proteins required for clotting and also binds to a dozen proteins involved in the complement system needed to kill pathogens or infected cells. Heparin binds to hormones, growth factors and their cell surface receptors. There are hundreds of proteins that use heparin to facilitate attachment to other proteins, to change shape and activity or to enter or leave cells. The point here is that heparin is a vivid example of a drug used to treat blood clotting, while at the same time dozens of other major interactions are ignored.

All drugs have multiple interactions with myriad proteins, but during screening, a drug is identified as having a significant desired affect. All drugs have side effects, because they are not completely specific. The side effects are often exploited as off-label uses for the drugs. Statins, for example, can impact lipid metabolism and change LDL blood levels. Unfortunately, research shows that lowering LDL does not affect heart disease. Fortunately, statins also lower inflammation and inflammation causes heart disease, so statins can be used as very expensive anti-inflammatory drugs.

The hopeful side is that most drugs are not necessary and there are other approaches that are more effective and cheaper to prevent and treat disease.

Don’t Worry about Your Gut Flora

There is a major NIH initiative to identify all of the bacterial species that live in or on the human body. That sounds potentially very useful in the context of all of the hype about pre- and probiotics. Your gut flora are important and people are doing very dumb things by killing off the bacteria that protect their skin from pathogens. The problem is that the concept of species of bacteria is wrong. In your gut, there is so much transfer of DNA between all of the different types of bacteria, that the idea of bacterial species doesn’t work.

Consider the pathogenic, toxin-producing E. coli strain. E. coli gets a bum rap, because we have created a new bacterium by treating cattle with antibiotics. The antibiotics increase fat accumulating in the beef, by altering the gut flora. The antibiotics eliminate some bacteria that normally live by adhering to the rectal areas of the cattle. E. coli can colonize the vacancies, but only if the gut lining releases nutrients and the E. coli is resistant to the antibiotics. The solution comes in the form of a plasmid from another bacterium. The plasmid is a small segment of DNA that carries genes for resistance to several different antibiotics and a toxin that causes intestinal cells to leak. The cattle don’t care much about the new Frankenstein E. coli, but if that plasmid-toting E. coli goes from cowpie to hamburger, and replaces your natural E. coli, it can be deadly.

The point is that the bacteria needed to fill all of the niches in your gut environment are created by approximation from the myriad genes of your whole gut flora community. You are constantly creating new “species” of bacteria. The problem is that you produce your own gut flora based on what you eat and by interactions with your gut. Those interactions can make you healthy or keep you sick. A single bottle of formula, for example, can permanently compromise the gut flora of a breastfed baby. We are learning how to control the development of healthy gut flora, probiotics, by supplements containing particular polysaccharides and oligosaccharides, i.e. prebiotics.

The hopeful side is that diets that have been shown to be healthy also produce healthy gut flora. That isn’t much of a surprise.

Don’t Worry about Toxins

The world is a dangerous place, but people have been there and done that. Plants have been standing around synthesizing a witch’s brew of natural toxins for millions of years. They are so good at it that even the most highly evolved species, bacteria, can’t eat them and survive. You can find a plant toxin that will interact with every human protein. That is why most human drugs are derived from plant toxins.

We know not to eat green potatoes, but pregnant women who make the mistake of eating rotten potatoes will regret the birth defects in their babies. There are so many toxins in plants that we have to be careful to watch what toddlers put in their mouths and every poison control center has to be able to identify plants over the phone to recommend emergency treatment. Pregnant women have a built in system to avoid plant toxins during the embryo’s most vulnerable first trimester. It is called morning sickness. A healthy diet during this time is to avoid vegetables and stick to meat and starch. Women build up baby fat to get through this sensitive time without exposure to plant toxins that their bodies may not be able to detoxify.

The happy thought here is that environmental toxins of human origin are not what make us sick, any more than eating plants generally is not a problem. With a healthy diet, even one modestly contaminated, we will not get sick. With a diet that compromises our health, even natural toxins become a threat.

Don’t Worry about Environmental Estrogens (except to save the rest of the animals)

There is an abundance of synthetic molecules that mimic human sex hormones, but once again, plants have been producing estrogen mimetics for millions of years. The second most abundant biological polymer (macromolecule), after cellulose, is lignin. Lignin is what makes up a large part of plant tissue and is what permits plants to be stiff. Lignin is also the “organic” material in fertile soil. This polymer is black in soil, because it is so complex that it has molecular structural components that can absorb all wavelengths of light. Lignin has no defined structure, but rather it is essentially a combination of thousands of structures.

Now imagine the mucky, black, lignin-laden banks of a forest stream. Tons of complex organic molecules leach into the stream and many of those molecules can mimic the shape of estrogens and bind to human molecules, receptors, that would normally bind to estrogen. It is possible to have excess estrogen leach from a sewage treatment plant, because it is not specifically targeted for removal, and the estrogens could temporarily reach a level to affect sensitive aquatic species, but there are already so many natural sources of estrogenic compounds, that the impact on humans would be expected to be unmeasurably small.

It is certainly possible for humans to pollute streams with other molecules, antimicrobial toothpaste ingredients, for example, that have unusually high environmental stability and bind with unnatural strength to estrogen receptors. Those would be problems like DDT. It would make sense to avoid exotic compounds and use natural plant products where possible, just because biological systems can digest them more readily.

The hopeful perspective here is that we already have ways of avoiding most of the problems with manmade estrogens and although these may be environmental hazards, they probably won’t affect human fertility.

An Anti-Inflammatory Diet and Lifestyle Is the Simple Solution

Prevention is the easiest way to stay healthy and since chronic inflammation is the foundation of degenerative, autoimmune and cancer diseases, an anti-inflammatory diet and lifestyle avoids most of the diseases. These same diseases also provide a modern description of aging, i.e. the consequences of mismanaged chronic inflammation. A healthy body is also the best protection from environmental threats, genetic weaknesses and the dangers of modern medicine.

The hopeful perspective for the New Year is eating and living well can keep you healthy and physically fit into your eighth decade.

ASP, C3 and Lipid Metabolism

Each gene codes for a protein with multiple molecular actions.

I was recently reading Nigee’s Diet and Nutrition Blog and was reminded of the interesting complexity of the molecular underpinnings of physiology. Nige was discussing fat metabolism and indicated that a protein called Acylation Stimulation Protein (ASP), increased triglyceride synthesis and that ASP levels in the blood increased after a lipid-rich meal.

Since I could recall nothing about ASP, I started to examine the gene that codes for ASP and soon found that it was called C3, as in complement C3. So the lipid manipulating function is part of the repertoire of the C3 protein that also regulates the innate immune system and is sometimes referred to as an anaphylaxin, in tribute to its ability to stimulate acute inflammatory responses (anaphylactic shock).

It is not unusual for a gene to code for multiple proteins with mix-and-match domains, as a result of alternative splicing events at the mRNA processing level. That is how different classes of immunoglobulins, IgG vs. IgE, can have the same variable regions for antigen binding, but different conserved regions for binding to other parts of the immune system. In the case of complement factor C3, a single protein interacts with dozens of different proteins and is involved many different cell and tissue functions.

The versatility of C3 is partly a result of having multiple pairs of basic amino acids that can participate in binding to heparan sulfate proteoglycans (HSPGs) on the surface of cells. C3 and all of the other proteins of the complement cascade have heparin-binding domains. Thus, the complement proteins are all bound together on the surface of cells by the strands of heparan sulfate. This brings the proteins all together for interactions and during an immune assault the complement components are ultimately assembled into tunnels that breach invading cells.

The ASP-C3 story shows that the complement system is also wedded to lipid metabolism. Another juxtaposition of lipids with immune function is the lipid deposition in athersclerosis and also the association between the ApoE4 type of lipoprotein and susceptibility to Alzheimer’s disease. Clearly, lipid metabolism is intimately associated with degenerative and autoimmune diseases, as well as cancer.