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An allergy is an exaggerated immune response or reaction to substances that are generally not harmful. Allergies are widespread in the population and have increased in prevalence and severity over the past 30 years in all industrialized countries. Allergies are thought to be the 6th leading cause of chronic disease.
Common allergens are pollen, mold, pet dander, dust, foods, drugs, insect bites, jewelry, cosmetics, spices, and other substances. Both genetics and environmental factors play a role in the development of allergies.
The immune system normally protects the body against harmful substances, such as bacteria and viruses. It also reacts to foreign substances called allergens, which are generally harmless and in most people do not cause a problem. But in a person with allergies, the immune response is oversensitive. When it recognizes an allergen, it releases chemicals such as histamines, which fight off the allergen. This causes allergic symptoms, which vary from person to person.
Common allergy symptoms:
• Breathing problems (coughing, shortness of breath, wheezing)
• Burning, tearing, or itchy eyes
• Conjunctivitis (red, swollen eyes)
• Diarrhea, stomach cramping
• Itching of the nose, mouth, throat, skin, or any other area
• Runny nose
• Skin rashes
• Stomach cramps
The Immune System
When the body comes under attack, it uses immune molecules called helper T-cells to produce cytokines. Cytokines are hormonal messengers that are responsible for biological effects in the immune system. The cytokines fall into two groups: those that are pro-inflammatory (these tend to fall within the Th1 branch of the immune system) and those that are anti-inflammatory (these tend to fall within the Th2 branch of the immune system).
Th1 and Th2 are polarised immune responses that should be fully-functioning. Unfortunately, if one of these immune branches becomes dominant, disease develops.
The Th1-type cytokines produce inflammation to kill intracellular parasites (parasites that live outside of the cell). When Th1 cytokines become dominant, they can contribute to the development of autoimmune diseases (ie. Insulin-dependent Diabetes, Multiple Sclerosis, etc).
The Th2 cytokines counteract the effects of the Th1 cytokines – they have an anti-inflammatory action. But they also help kill extracellular pathogens (viruses and bacteria that live outside of the body’s cells). When Th2 cytokines become dominant, they can induce a pronounced allergic response and atopy (a genetic tendency to develop classic allergic diseases such as rhinitis or runny nose, asthma, and eczema). If you suffer from allergies or atopy, you are likely over-producing the Th2-types of cytokines and have a Th2-weighted imbalance.
A new set of T-helper cells has been identified: the Th17 cells. These are found where the body’s internal and external environments interact, such as the skin and the lining of the intestinal tract. They attack bacteria on those surfaces, but with accompanying inflammation. Th17 cells are thought to be implicated in: Crohn’s disease (an inflammation of the small intestine), ulcerative colitis (inflammation of the large intestine), and psoriasis (inflammation of the skin). I’m not going to discuss these cytokines today but just wanted to draw attention to the fact that a third set of cytokines does exist.
Establishing Balance Within the Immune System
In a well-functioning immune system, Th1 and Th2 cytokines are both produced by the helper T-cells, and work together to keep everything in balance.
Researchers working on allergies are looking at ways to drive up the Th1 response – to rebalance the system away from leaning heavily into a Th2 response by redirecting the body into using the Th1 cytokines instead. Likewise, researchers working with diseases where the Th1 response is driving the system, are looking at using high-dose exposure to allergens to ‘kick-start’ the Th2 immune response, and rebalance the system.
An additional strategy is being used to prevent the onset of disease; this involves the study of pregnancy and early postnatal life. Both of these states are chiefly viewed as Th2 dominant (to reduce the risk of miscarriage, a strong Th2 response is necessary to modify the Th1 cellular response in utero). The fetus can switch on an immune response early in pregnancy, and because pregnancy is chiefly a Th2 situation, babies tend to be born with Th2 biased immune responses. It is hypothesized that babies who go on to develop full blown allergies may be born with a generally weaker Th1 response, although it is becoming apparent that babies with allergies actually produce both weak Th1 and Th2 responses.
There are many theories that may explain a tilt in Th1/Th2 balance toward Th2. These may include the decreasing incidence of infections in the industrialized world—a concept known as the hygiene hypothesis; the increasing success of immunizations and antibiotic therapies that deprive the body of signals that promote Th1 development; increased pollution; or exposure to environmental products that activate Th2 cells.
The shift in balance of Th subsets toward a polarized Th2 response is generally accepted to occur in atopic and allergic disorders and may account for the great increase seen in allergic diseases over the last 3 decades.
The Allergic Process
The term “allergy” is most commonly associated with IgE- mediated hypersensitivity. IgE is an immune molecule that is associated with allergies. In susceptible individuals, the first exposure to an allergen (ie. peanut) causes a mild immune response that sensitizes the immune system so that it will recognize the substance when presented again. In this first exposure to an allergen, no symptoms are typically seen. The second exposure and subsequent exposures to this very same allergen usually result in symptoms.
The first time an allergen enters the body, it favors Th2 development and IgE production. These IgE molecules attach themselves to the surfaces of mast cells (concentrated in the lungs, skin, tongue, and linings of the nose and intestinal tract) or basophils (in circulation) and remain bound to them for weeks or months.
Second and Subsequent Exposures
The next time a person comes in contact with the same allergen, it will bind to the IgE antibodies, which are already present on the surfaces of mast cells and basophils after the initial exposure to the allergen. This process leads to the development of an “allergen-antibody” complex, which activates the mast cell or basophil and causes them to open up and release mediators (ie. histamine, proteases, chemotaxins, leukotrienes, prostaglandins) into the bloodstream.
These mediators induce localized inflammation and other responses that cause symptoms associated with allergy. Because mast cells and basophils can be located in diverse areas of the body, allergic symptoms can occur in a variety of locations and cause such varied symptoms as mucus production/nasal congestion, hives, coughing, wheezing, muscle spasm, itchy and watery eyes, swelling, and nausea.
There are 5 common approaches to the treatment of allergies, such as avoidance, medication, immunotherapy, natural therapy or achieving Th1/Th2 balance, and natural therapy that targets the allergic cascade.
1) Avoidance: Avoiding the allergen causing your symptoms is the ideal approach to treatment. Unfortunately, many allergens cannot be avoided.
2) Medication: Common medications include anti-histamines, decongestants, sodium cromoglycate, nedocromil sodium, and leukotriene antagonists. These medications are treating the symptoms of allergies. Remember above when I mentioned that when the allergen-antibody complex activates the mast cell or basophils to release mediators (ie. histamine, proteases, chemotaxins, leukotrienes, prostaglandins)? Well, it is these mediators that the common allergy medications are working on. For example, anti-histamines inhibit the action of histamines by blocking it from attaching to histamine receptors, thereby treating symptoms of allergies, such as runny nose and watery eyes. Although effective, some of these medications can cause some side effects, such as drowsiness, sedation, and hyperactivity, making them unappealing to many patients. More concerning, however, is that the long-term use of high-doses of corticosteroids, particularly when taken orally, can result in numerous side effects including facial swelling, muscle weakness, peptic ulcer, osteoporosis, cataracts, and a reduced growth rate in children. Furthermore, relief from these common allergy medications is often temporary and works downstream to just treat the symptoms of allergies. They do not help to establish Th1 and Th2 balance.
3) Immunotherapies: While other common allergy medications treat only the symptoms of allergic disease, immunotherapy can modify the natural course of the allergic disease, by reducing sensitivity to allergens. A three-to-five-year individually tailored regimen of injections may result in long-term benefits. It does not work for everyone and is only partly effective in some people, but it offers allergy sufferers the chance to eventually reduce or stop symptomatic/rescue medication. This type of therapy is most indicated for people who are extremely allergic or who cannot avoid specific allergens. Although effective, immunotherapy is both time consuming and expensive. This is not a therapy that is offered at the Natural Way Health Clinic.
4) Natural Therapies for Re-establishing Th1 and Th2 Balance: Inhibiting Th2-type cytokines may downregulate an overactive Th2 response. In addition, inducing the Th1 response and the production of its cytokines may shift the system and produce balance in some individuals. Many nutritional factors and herbs are thought to influence Th1 and Th2 responses. By addressing this initial step in the allergic process, the incidence and/or severity of an allergic reaction may be manipulated.
5) Natural Therapies that Target the Allergic Cascade: Combining Th1/Th2 balancing therapies with natural therapies that address certain downstream events may offer even greater protection and/or relief.
(a) Because of the very significant role played by IgE in the development and propagation of allergic inflammation, inhibiting IgE production creates an important target for intervening in the allergic cascade.
(b) When mast cells and basophils open up and release chemicals (ie. histamine), various tissues are affected and produce allergic symptoms. This perpetuates the Th2 polarization and inflammation, while continuing the allergic response. Reduction of these mediators or inhibition of their activities may play an important role in providing relief to those suffering from allergic disease.
(c) Arachidonic acid (AA), an omega 6 fatty acid, is released from the mast cell or basophil cell membranes when they open up and release the chemical mediators. Different enzymes, called lipoxygenase and cyclooxygenase metabolize arachidonic acid to produce potent pro-inflammatory molecules, called leukotrienes and prostaglandins. Both leukotrienes and prostaglandins are involved in the allergic process and cause such symptoms as constriction of the airways in the lungs (ie. leading to shortness of breath, wheezing, and coughing) and narrowing of the blood vessels (ie. leading to increased heat and itching in the skin). Limiting or inhibiting the formation of these inflammatory molecules is a critical and necessary component of any anti-allergy therapy.
(d) Low tissue antioxidant levels are associated with allergies and asthma, while inflammatory cells involved in the allergic process generate and release reactive oxygen species, which can promote damage of affected tissues. Combating these harmful free radicals with antioxidants is another important aspect of therapy.