Epigenetics: Strengthening the Immune System
This report provides an overview of epigenetics. Part (A) covers the relationship between epigenetics and the immune system, highlighting its role in cellular memory and how it differs by gender and changes as we age. Part (B) suggests methods of boosting the immune system via epigenetics, including physical activity and healthier eating. Full details are provided below.
Part (A): This section provides insights on the link between epigenetics and the immune system.
Epigenetics Form the Basis of Molecular Cellular Memory
- When a single gene has a chemical compound added to it and the compound regulates the gene's activity in some way, the gene has undergone an epigenetic change. The combination of these changes is referred to as the epigenome.
- These chemical compounds do not modify the genetic sequence, but instead attach themselves to the top of the molecular strand.
- When a cell divides through meiosis or mitosis, some epigenetic changes attached to its genetic sequence can be replicated as well.
- In this way, epigenetic changes form the basis of generational cellular memory (meaning the changes that are passed on from a parent cell to its offspring), thus forming the evolving immune system response.
- As an example, epigenetic mechanisms have been demonstrated to influence the regulation of T and B lymphocytes, both of which has a major role in the immune system.
Environmentally-influenced Epigenetic Modifications Can Weaken Immune System
- Epigenetic changes can stem from either intrinsic (metabolic profile or hormones, for example) or extrinsic (diet, pollution, or stress, as examples) sources.
- An individual's lifestyle is said to "significantly" affect the epigenome.
- Eating less produces an epigenetic effect that reduces the metabolic rate and has been demonstrated to contribute to a 20 percent longer lifespan in mice.
- Obesity in adolescents produces an epigenetic effect (DNA methylation) that alters blood cells and increases harmful oxidative exposure.
- Changes to the environment of a parent can yield improvements to its offspring even if those changes don't manifest in the parent. For example, a parent mouse with the Agouti gene is susceptible to obesity, diabetes, and certain cancers. It is also yellow. When fed B vitamins, the parent does not recover; however, the offspring of these mice have a suppressed Agouti gene. This means they have no susceptibility to the health vulnerabilities of their parents, and they are brown rather than yellow.
Epigenetic Changes Vary with Age and Gender
- Aging is associated with a declining immune system response as a result of epigenetic changes that affect the regulation of key disease-fighting agents such as T and B lymphocytes.
- Aging causes oxidative stress, which in turn causes epigenetic effects. As an example, SIRT-1 (a histone deacetylate) decreases in protein level as an individual ages, causing an increase in the acetylation of lysine 16 of histone H4K16.
- Age-related epigenetic changes resulting in declining T cells and increasing monocyte and cytotoxic cell functions happen at a greater magnitude in males.
- For both men and women, age-related epigenomic changes experience an initial spike around the late-30s.
- A second spike of age-related epigenomic changes occurs earlier and stronger in men.
- Epigenomic differences accelerate after age 65, leaving males with higher innate and pro-inflammatory activity and lower adaptive activity.
Part (B): This section provides insights on methods of combating viruses and diseases from an epigenetic standpoint.
Foods to Avoid
- Epigenetic changes caused by the Western diet may not all be reversible even when a healthier diet is adopted. Eating a cereal-based diet for 4 weeks improved the acute inflammation response in mice after eating a heavy Western diet; however, many of the changes to the immune system were not reversed.
- Food that is high in calories contributes to negative epigenetic changes in the immune system and should be avoided. High calorie food is treated like a bacterial infection by the immune system, causing an overactive response.
- Food that is high in fat contributes to negative epigenetic changes in the immune system and should be avoided. High fat food is also treated like a bacterial infection by the immune system, causing an overactive response.
- Food that is low in fiber contributes to negative epigenetic changes in the immune system and should be avoided.
- Fast food contributes to negative epigenetic changes in the immune system and should be avoided.
Foods to Eat
- Eating foods high in zinc such as meats and shellfish improves the immune system's response to inflammation and thus improves health outcomes for cancer, diabetes, and other diseases. For adults, 8-11 mg of zinc should be consumed each day.
- Fruit has a different effect on the immune system than juice. Fruit improves macrophage modulation while juice improves B and T cell modulation. This suggests both fruit and juice are important for immune system health.
- Foods that are high in vitamin A are recommended as vitamin A has a proven role in affecting the innate and the adaptive immune system. The recommended dietary allowance for men is 900mcg. For women, it is 700mcg.
- High vitamin A foods include liver, king mackerel, salmon, bluefin tuna, goat cheese, hard-boiled eggs, and cream cheese.
- A vegetarian diet contributes to an improved immune system due to the regular consumption of lower-fat, higher-vitamin foods. Plant-based diets tend to be higher in fiber, which improves immune system response.
- Probiotic-heavy foods such as yogurt and kefir improve the immune system response and limit the effects of various inflammatory disorders through epigenetic mechanisms.
All forms of physical activity appear to have an effect on the immune system.
- Physical activity plays a critical role in influencing epigenetic changes that improve the reaction of the immune system.
- Physical activity delays the onset of aging. Aging contributes to immune system decay through epigenetic mechanisms.
- The effect of physical activity on improving particular conditions (such as hypertension) is based on the genetic predisposition of the individual patient. As such, personalized exercise prescriptions are the best method of improvement.
- Increased physical activity leads to decreased levels of lymphocytes in circulation, thus decreasing the inflammation response of the immune system. This is particularly beneficial for immune system disorders caused by an overreaction of the inflammatory response.
- Women that performed an incremental step test (beginning with a 3-minute warm up at 50 watts power output, and then increasing in power at increments of 25 watts every 2 minutes until exhaustion) had an increase in natural killer cells while exercising and then experienced a drop in natural killer cells for up to 48 hours afterwards. Natural killer cells play a role in overactive immune system responses (including arthritis and diabetes), meaning that having less can be favorable.
- Resistance-based exercises cause epigenetic changes that lead to healthy skeletal muscle by improving energy metabolism and insulin sensitivity. Endurance-based exercises caused additional metabolic alterations. Both resistance- and endurance-based exercises are recommended to thwart diseases.
- Low-intensity exercises (such as tai chi) undertaken by women for at least 3 years has shown epigenetic improvements in immune system changes associated with aging.