Green Tea Holds Potential as Therapy for Inflammatory Skin Diseases

Those treated with green tea showed slower growth of skin cells and the presence of a gene that regulates the cells' life cycles.

"Psoriasis, an autoimmune disease, causes the skin to become thicker because the growth of skin cells is out of control,” stated Dr. Stephen Hsu, an oral biologist in the Medical College of Georgia (MCG; Augusta, USA) School of Dentistry and lead investigator on the study, which was published in the August 18, 2007, issue of the journal Experimental Dermatology. "In psoriasis, immune cells, which usually protect against infection, instead trigger the release of cytokines, which causes inflammation and the overproduction of skin cells.” Other autoimmune diseases with similar side effects include lupus, which can lead to skin lesions and dandruff.

Green tea, already shown to inhibit inflammation, helps by regulating the expression of caspase-14, a protein in genes that regulates the life cycle of a skin cell. "That marker guides cells by telling them when to differentiate, die off, and form a skin barrier,” Dr. Hsu noted. "In people with psoriasis, that process is interrupted and the skin cells don't die before more are created and the resulting lesions form.”

Lab animals treated with green tea also demonstrated decreased levels of proliferating cell nuclear antigen (PCNA), a gene expressed when skin cells multiply. In psoriasis, the gene is overexpressed and speeds production of skin cells.

"Before treatment, the antigen, PCNA, was present in all layers of the skin,” Dr. Hsu said. "Typically, PCNA is only found in the basal layer, the innermost layer where skin cells continually divide and new cells push the older ones to the skin surface, where they eventually slough off. After being treated with green tea, the animal models showed near-normal levels of PCNA in only the basal layers.”

This study is significant, according to Dr. Hsu, because some treatments for psoriasis and dandruff can have hazardous side effects. "The traditional treatment of ultraviolet light and medication, while it can control the lesions and be used long term, may cause squamous cell carcinoma--the second most common form of skin cancer,” Dr. Hsu said. "Some of the most effective anti-dandruff shampoos also have carcinogens in them. While the U.S. Food and Drug Administration allows that in small amounts, the bottom line is that we don't know the long-term effects of using those products continuously.”

Green tea, which is plant-derived, may be an option, according to Dr. Hsu. But scientists must work to overcome some barriers with the treatment. The compounds in green tea are so active that they are oxidized too rapidly when combined with other ingredients. They also dissolve in water, which cannot penetrate the skin's barrier. Researchers are looking for a balanced formula that can dissolve in fats, which can permeate the skin.


Related Links:
Medical College of Georgia