Feeling itchy? it may be stress!

German and Canadian researchers are suggesting that stress may make people itch - they say stress possibly activates immune cells in the skin and inflames it.

The scientists from the University of Medicine in Berlin and McMaster University in Canada, suspected that stress could exacerbate skin diseases by increasing the number of immune cells in the skin.

In order to test this hypothesis, they exposed mice to sound stress and found that the stress challenge resulted in higher numbers of mature white blood cells in the skin.

The researchers lead by Dr. Petra Arck of Charité, University of Medicine Berlin also found that by blocking the function of two proteins that attract immune cells to the skin the stress-induced increase in white blood cells in the skin was prevented.

The researchers say the skin provides the first line of defence against infection and acts not only as a physical barrier, but also as a site for white blood cells to attack invading bacteria and viruses. But the immune cells in skin can over-react, resulting in inflammatory skin diseases such as atopic dermatitis and psoriasis and stress can trigger an outbreak in patients suffering from such inflammatory skin conditions.

The researchers say the cross talk between stress perception, which involves the brain, and the skin is mediated the through the "brain-skin connection" but little is known about the means by which stress aggravates skin diseases.

Dr. Arck's team found that the proteins LFA-1 and ICAM-1 played a key role in promoting the inflammatory skin reaction and they suggest that stress activates immune cells, which in turn are central in initiating and perpetuating skin diseases. They say the goal of future studies is to prevent stress-triggered outbreaks of skin diseases by recognizing individuals at risk and identifying immune cells suitable to be targeted in therapeutic interventions.

The research appears in the November issue of The American Journal of Pathology.