Green Tea Holds Promise As New Treatment For Inflammatory Skin Diseases

Researchers studied an animal model  for inflammatory skin diseases, which are often characterized by patches of  dry, red, flaky skin caused by the inflammation and overproduction of skin  cells. 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," says Dr. Stephen Hsu, an oral biologist in the MCG School of  Dentistry and lead investigator on the study published in the Aug. 18 edition  of 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  suppress 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  says. "In people with psoriasis, that process is interrupted and the skin cells  don't die before more are created and the resulting lesions form." 

Animal models treated with green  tea also showed reduced levels of proliferating cell nuclear antigen, a gene  expressed when skin cells multiply. In psoriasis, the gene is over-expressed  and speeds production of skin cells.

"Before treatment, the antigen,  PCNA, was present in all layers of the skin," Dr. Hsu says. "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 research is important because  some treatments for psoriasis and dandruff can have dangerous side effects, he  says.

"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 says. "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 alternative, he says. But scientists must work to overcome some  barriers with the treatment.

  The chemicals in green tea are so  active that they are oxidized too quickly when mixed 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, Dr. Hsu says.