Printable version of the article  Th1/Th2 Balance: A Natural Therapeutic Approach To Th2 Polarization In Allergy

Th1/Th2 Balance: A Natural Therapeutic Approach To Th2 Polarization In Allergy

A Summary

By Tom Sult, M.D.

Allergic respiratory diseases have increased in prevalence and severity over the past 30 years in all industrialized countries. The occurrence of allergic rhinitis (hay fever) alone has increased substantially over the past 15 years, accounting for approximately 16.7 million office visits to healthcare providers each year. Allergies are also a significant trigger of asthma. According to the Centers for Disease Control and Prevention, more Americans than ever before (over 15 million) suffer from asthma, transforming what was a relatively inconspicuous ailment into an epidemic illness of significant public health concern. Recently, the role of T helper (Th) cells in the development of allergic disease has been described.

THE SIGNIFICANCE OF T-HELPER CELLS
Th cells are the regulators of the immune system. After stimulation by any antigen (e.g., allergen, pathogen) that has entered the body, Th cells can develop into either Th1 or Th2 cells that trigger different immune processes, which protect the body in different ways. Whether Th cells develop into Th1 or Th2 cells is dependent on a variety of factors including the type of antigen, genetics, certain regulatory proteins (cytokines), and other factors. Researchers have found that imbalanced Th1/Th2 immune responses are linked to certain immune-related disorders. For instance, a Th1-dominated immune response has been implicated in organ-specific autoimmune disease (e.g., type 1 diabetes, thyroiditis) while a Th2-dominated immune response can lead to allergic disorders and systemic autoimmune disease (e.g., lupus). Such imbalanced immune activity can be caused by a number of things including genetics and environmental factors.

TARGETS FOR TREATMENT: TH1/TH2 BALANCE AND DOWNSTREAM PROCESSES
Because those with an overactive Th2 response are often afflicted with allergic disease, the goal of allergy treatment should address downregulating the Th2 response and/or upregulating the Th1 response to produce a balance. In addition to balancing Th1 and Th2, treatment strategies should also address downstream processes including IgE production, histamine release, inflammation, and oxidative stress.

IgE Production—IgE is a type of antibody that, despite offering protection against certain pathogens, is responsible for driving hypersensitivity reactions such as hay fever, asthma, hives, and anaphylaxis.

Histamine Release—Histamine is released during an allergic reaction and it perpetuates allergic inflammation and the Th2 response.

Inflammatory Compound Production—Leukotrienes and prostaglandins are inflammatory mediators involved in the allergic process. They can cause symptoms such as constriction of the lung passageways and blood vessels and tissue swelling.

Oxidative Stress—Low antioxidant levels are associated with allergies and asthma. In addition, inflammatory cells involved in the allergic process release harmful free radicals.

NATURAL SUBSTANCES FOR THE TREATMENT OF ALLERGIC DISORDERS
Research suggests that the following natural compounds have the ability to modulate the allergic response thereby offering an excellent alternative to conventional therapies whose chronic use is often accompanied by several side effects.

Perilla Seed Extract—Perilla seed extract (Perilla frutescens) has long been used in Traditional Chinese Medicine (TCM) and in Kampo—a Japanese variant of TCM. It is capable of modulating multiple processes in the allergic response, including histamine release, leukotriene synthesis, and oxidative stress. In addition, preliminary research performed in Japan suggests that perilla seed extract may suppress Th2 responses.

Omega-3 Fatty Acids—The increased prevalence of atopic disease has recently been associated with the over consumption of omega-6 fatty acids in relation to omega-3 fatty acids—an unhealthy imbalance common in the Western diet. Research suggests that a balanced intake of these fatty acids may have a powerful, positive effect in certain patients with allergic disorders.

Vitamin E—Research suggests that vitamin E may protect against allergies and allergic disease not only by reducing the associated free radical damage, but also by influencing Th2-type cytokine expression, IgE levels, and inflammatory compound production.

Probiotics—"Friendly" bacteria such as Lactobacillus acidophilus and Bifidobacteria may help alleviate allergic inflammation and shift Th2-dominated immune responses, thereby reducing allergic symptoms.

Adaptogens—Adaptogenic herbs such as cordyceps (Cordyceps sinensis), ashwagandha (Withania somnifera), and Asian ginseng (Panax ginseng) may reduce the negative effects of acute or chronic stress. Research suggests that stress may promote an increased Th2 response, thus escalating susceptibility to allergic disorders.

Vitamin C and Flavonoids—Flavonoids possess anti-allergic, anti-inflammatory, antiviral, and antioxidant activity. In addition, flavonoids have been shown to inhibit the release of histamine. Similar to flavonoids, data from animal and human studies have shown that vitamin C supplementation results in reduced histamine release and improved lung function.

Turmeric, Ginger, and Boswellia—Turmeric (Curcuma longa), ginger (Zingiber officinale), and boswellia (Boswellia serrata) are popular herbs used within Ayurveda—an East Indian system of medicine. These herbs have been shown to inhibit the production of inflammatory compounds involved in an allergic response.

Xin Qin Ke Li —This traditional blend of Chinese herbs including astragalus (Astragalus membranaceus), Chinese skullcap (Scutellaria baicalensis), schizonepeta (Schizonepeta tenuifolia), fragrant angelica (Angelica dahurica), atractylodes (Atractylodes macrocephala), and other herbs supports Wei ch'i—said to be the body's "protective shield." This formula is primarily used in China to treat colds, allergic rhinitis, acute and chronic rhinitis, nasosinusitis, and other sinus and nose ailments.

CONCLUSION
As the incidence and suffering associated with allergic disorders continue to grow, so does the knowledge regarding its prevention and treatment. By addressing Th1/Th2 imbalance and associated processes, natural therapies may bring lasting relief to patients.

Advanced Nutrition Publications ©2002

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