Skin: your first line of defence
The skin, often referred to as the largest organ in the body, has three layers and is the interface between the human body and the external environment. It senses, (via hairs and nerve endings) and responds to environmental conditions, maintaining the internal organs (liver, kidney, heart, brain etc) within a narrow range of conditions required for health. Skin has a major role in the control of temperature, hydration, acid/base levels, via sweat and oil glands, adipose tissue and the blood circulating in the skin.
As well as being a physical barrier (the epidermis), the skin plays an active role in response to injury and infection, and is a key site for immune activation. Keratinocytes in the dermis synthesise many inflammatory mediators that activate innate (immediate) and adaptive (long term) immunity. Langherhans cells (about 10% of the epidermal cells) are antigen presenting cells (APCs) that take up and process foreign substances, with migratory dendritic APC they interact with T lymphocytes, initiating adaptive immune responses, including cytotoxic, helper and memory T cells and antibody producing B cells. Thus the skin is a primary site for recognition of self-non-self antigens and disruption of this function can lead to autoimmunity or chronic infection.
(www.skinhttpfaculty.ircc.edufacultytfischerAP1skin.jpg.Pearson Education 2004)
General principles in treating common disorders of the skin
Common skin disorders include; contact dermatitis, atopic eczema, acne, viral infections (eg Herpes and warts), bacterial infections (eg impetigo), skin cancer and psoriasis. Less common disorders include systemic autoimmunity and genetic defects (eg Lupus, alopecia, sclerosis) (Weller et al 2008). The general principles of treatment are:
1. To sooth and protect the damaged skin
2. To moderate inflammation, and where possible by protection against or elimination of the initiating agent (allergen, pathogen).
3. To initiate wound healing processes
4. To treat any systemic dysfunction that initiated or prolonged skin disease.
Non herbal treatment includes anti-virals and antibiotics to clear infections, topical and internal corticosteroids to reduce inflammation, and immunosuppressive drugs to treat autoimmune and chronic inflammation (Upfal 2002). While these are very useful for relief of symptoms, they often cannot provide a return to normal function and their long term use can further damage the immune system.
Key herbal actions in the treatment of skin conditions.
Herbal treatment aims are the same as those listed above, although there is much greater emphasis on the restoration of normal function and prevention of recurrent disease. Herbal therapy is most useful for chronic diseases such as atopic eczema, acne, chronic infections (eg Herpes and warts) and chronic inflammatory autoimmune diseases such as psoriasis and Lupus (Mills and Bone 2000).
For topical soothing of the skin, demulcent herbs rich in mucilage (polysaccharides) and saponins, such as Aloe vera, chickweed (Stellaria media) and comfrey (Symphytum officinale) are used (Mills and Bone 2000). These topical anti-inflammatory preparations include tannins and polypenols that cool and coat the skin and promote wound healing.
For internal treatment, depuratives that reduce inflammation, and adaptogens (eg Eleutherococcus senticosus and Panax ginseng ), that modulate immune responses, are the most useful therapies for long term relief.
Mills, S. and Bone, K. 2000. Principles and Practice of Phytotherapy. Churchill Livingstone. Sydney, Australia,
Upfal, J. 2002. The Australian drug guide. Schwartz Publishing Pty Ltd. Melbourne, Australia,
Weller, R., Hunter, J., et al. 2008. Clinical Dermatology. Blackwell Publishing. Carlton, Vic, Australia,